DE2207732A1 - Process for the production of ferrites - Google Patents

Description

PATENT LAWYER'S OFFICE ThOMSEN - TlEDTKE - BüHLING

TEL. (MII) S3 0211 TELEX: S-24 303 lopat 9 9 Π 7 * 7 '"i 9

PATENT LAWYERS Some: Frankfurt / M .:

Dipl.-Chem. Dr. D. Thomson DIpI. - Ing.W. Wtlnkiuff Dipl.-Ing. H. Tiedtke (Fuchshohl 71)

Dipl.-Chem. Q. Bühllng Dipl.-Ing. R. Kinne Dipl.-Chem. Dr. U. Eggers

8000 Munich 2

Kalser-Ludwlg-Platz 6 February 18, 1972

Imperial Chemical Industries Limited London (Great Britain)

Process for the production of ferrites

The invention relates to the manufacture of ferrites.

Ferrites, for example manganese / zinc ferrite, are usually prepared by using iron oxide and the oxides, carbonates or hydroxides of the other metals which should be present in the ferrite, mixed together if necessary filtered and calcined at temperatures of, for example, 900 to 1000 ° C., a ferrite being formed. The ferrite thus formed is ground in a ball mill, so that particles of a suitable size are formed which are pressed and sintered to produce a ferrite mass

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yjndllrtt * agree to Intbetondar · by phone, btdürlen »chrlftlldier BeatAtlgung Potl "ch" ok (Munich) Account 1168/4 Drttdn.r Bank (Munich) Account 5660700

which has the combination of required properties. This method of creating ferrite masses has the following Difficulties on:

1. It is difficult to make a ferrite mass homogeneous in structure especially when some metals are only to be incorporated in trace amounts.

2. The ferrite originally produced must be subjected to several grinding stages, while it is contaminated
can be added.

According to the invention, a method for producing a ferrite is created in which an aqueous solution, which has a soluble iron salt and a soluble salt of at least one other metal, which the latter is able to be precipitated as carbonate from aqueous solution, with ammonium carbonate or - bicarbonate is implemented to precipitate a carbonate mixture, and the precipitated carbonate mixture
is heated to form a ferrite. That so educated
Ferrite can be calcined, granulated, pressed into a suitable shape and sintered to form a ferrite mass with the combination of the required properties
forms.

The method according to the invention can be used

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to either use soft ferrites such as manganese / zinc, Copper / zinc or nickel / zinc ferrites, or hard ferrites like for example, barium ferrite. The method is particularly suitable for preparing soft ferrites with very desirable ones Combinations of properties, these ferrites being low Contain quantities of one or more trace metals, e.g. zirconium, chromium, copper, magnesium, silicon, Barium, cobalt, aluminum, nickel, strontium or especially vanadium, calcium or titanium, in addition to the metallic ones Main components of ferrite. A ferrite that shows a particularly suitable combination of properties and after -The process according to the invention can be produced is manganese / zinc ferrite with a content of calcium and / or titanium as trace metals. The trace metals are preferably in the Ferrite incorporated in amounts up to about 0.5%. A manganese / zinc ferrite, which contains calcium and titanium as trace metals, preferably contains up to about 0.3% calcium and up to about 0.2% titanium.

Soluble metal salts, including trace amounts " metals, which should be present in the ferrites (or brine, which can be precipitated, for example SiO ^), are incorporated into the aqueous solution, which with the carbonate or bicarbonate is implemented. Suitable salts include

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Nitrates, sulfates and chlorides or their mixtures. The soluble iron salt is preferably a ferrous salt, which with different amounts of ferric salts can be mixed. The solution containing the metal salts is preferably added to the ammonium carbonate or bicarbonate, which is preferably in aqueous solution.

The concentrations of the soluble salts of the main constituent metals used to prepare the aqueous Solution are used with which to react the carbonate or bicarbonate, vary according to the temperature and the solubility of the salt. Preferably these solutions are in the vicinity of the saturation concentration around the volume reduce the reaction mixture. If desired, the temperature at which the reaction is carried out can be can be increased to allow the use of more concentrated solutions. A concentrated solution of the carbonate or bicarbonate is usually used to keep the volume of the reaction mixture to a minimum.

After the solution containing the metal salts has been mixed with the carbonate or bicarbonate, the mixture is preferably aged by standing it at a temperature of, for example, 20 to 50 ° C, especially 30 to 40 ° C, with a minimum of stirring for a period of time , preferably 1 to 1 1/2 hours, heated before the precipitated

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Filtered off carbonates. The precipitate can be washed with, for example, dilute aqueous ammonia, for example To remove sulfate ions, and it is preferably dried at a temperature of 100 to 120 ° C.

The pH of the mixed solutions is alkaline. To reduce or avoid the formation of ammine complexes, if, for example, zinc ·? If nickel or copper salts are to be precipitated, the pH value is preferably maintained at a minimum value which is consistent with ensuring good precipitation, preferably within of the range from 8 to 8.7, in particular between 8 and 8.4. It is very convenient to adjust the pH of the mixed solutions to measure during the aging period and, if necessary, to adjust.

The powders which are formed by drying the co-precipitated carbonates partially have decomposed carbonate. These are very reactive and have large surface areas. It is possible this Powder before heating to produce a ferrite, modified by adding other elements. As well as Major and minor components of the ferrite can be added in this way will. If the powder is heated to form ferrites, the additives react with the carbon dioxide that has precipitated out together.

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naten with the formation of substances which can be sintered to produce ferrite masses with modified magnetic and electrical properties. The addition can be done in a variety of ways. If the element to be added forms a soluble salt which can be precipitated with an alkali, the precipitation can be carried out on a slurry of the powder. If the element forms a decomposable salt, for example a nitrate, or a suitable sol, for example SiO ₂ , it can be added to a slurry of the powder. If the element does not form a suitable inorganic compound, it may be incorporated in the form of a suitable organometallic compound.

The ferrite is formed by heating the precipitated carbonates, preferably to a temperature above 500 C, in particular to a temperature in the range from 800 to 1000 C ₁ , the ferrite being obtained in a form which is suitable for pelletizing and sintering.

The inventive method facilitates the production of ferrites of homogeneous composition, especially when it is necessary that traces of metals such as titanium and calcium are present in the ferrite. The physical composition of the ferrites produced after heating to 800 to 1000 C is such that it may often be unnecessary to use this

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To grind product before pressing and sintering, thereby the risk of impurities being introduced during milling is avoided.

The use of ammonium carbonate for precipitation of the ferrite components is advantageous because it does not introduce any deleterious alkali cations such as sodium, and also because it does so the precipitation of calcium is made possible. The carbonate precipitate produced does not tend to be caused by sulfate ions to be contaminated, as is the case when hydroxides are precipitated.

The invention is illustrated in more detail by the following exemplary embodiments:

example 1

Solution A;

A mixture of:

(1) 999O.5 g of ferrous sulphate stock solution containing of 2.95 g iron per 1OO g solution,

(2) 641.3 g of hangano sulfate solution containing 10.05 g manganese per 1OO g solution,

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(3) 562.5 g zinc nitrate solution with a content of 13.9 g zinc per 100 g solution,

(4) 47.4 cm calcium nitrate solution with a content of 28.0 g calcium nitrate tetrahydrate per 250 cm solution,

(5) 16.0 cm ^{3 of} titanosulfate solution (15%).

Solution A is heated to about 70 ° C. and then slowly added to the ammonium carbonate solution (about 2.4 molar) until the pH is 8-15. The excess of alkalinity in the lye corresponds to 8.3 cm 0.5 niICl per 50 cm of filtered lye (using methyl orange as an indicator). The precipitate is aged for 60 minutes with slow stirring at about 40 ° C., filtered off and then washed free of sulfate ions with deionized water. The filter cake is then dried overnight at 110 ^° C.

The powder produced is calcined in air at 870 ° C. for 1 hour. Then 10% of a 4% strength aqueous polyvinyl alcohol solution is used added and takes a Vorpelüetisiert at about

2
700 kg / cm before. This pellet is then broken into granules

2 liters of about 425 microns and then compresses at about 2460 kg / cm in Toroids »The toroids are compressed by placing them in a mixture of 2% oxygen and at 125O ° C for 2 hours 98% nitrogen sinters, producing a ferrite mass with the following properties

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Loss χ ΙΟ ⁶ at 100 KHZ; 2.8
initial permeability 3079

Example 2

Solution B;

A mixture of:

(1) 1767.0 g of ferrous sulfate stock solution containing of 2.78 g iron per 100 g solution,

(2) 106.9 g of manganese sulfate solution containing 10.05 g manganese per 100 g solution,

(3) 93.7 g zinc nitrate solution with a content of 13.9 g

Zinc per 100 g solution »

(4) 7.9 cm calcium nitrate solution containing

28.0 g calcium nitrate tetrahydrate per 250 cm solution,

(5) 2.7 cm ³ titanosulphate solution (15%),

(6) 6.4 cm nickel sulphate solution with a content of 1.5 g nickel sulphate heptahydrate per 100 cm solution.

Solution B is reacted with ammonium carbonate solution under the conditions described in Example 1, the pH being 8.20 and the excess alkalinity corresponding to ^{3.8 cm 3.}

The powder produced after drying is calcined at 890 ° C. in air for one hour. Then you put 10% of a 4%

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aqueous polyvinyl alcohol solution and the powder is

prepelletized at about 400 kg / cm. This pellet is broken into granules about 425 microns and then pressed at about 2320kg / can to toroids.

The toroids are finally compressed by sintering them for 2 hours at 1250 C in a mixture of 2% oxygen and 98% nitrogen, a ferrite mass being produced which has the following properties: losses χ 10 ⁶ , 3.2; initial permeability 4Ο85.

Example 3

Solution C t

A mixture of:

(1) 836.8 grams of ferronitrate stock solution containing of 2.39 g iron per 100 g solution,

(2) 58.0 g manganese nitrate solution with a content of 7.54 g manganese per 100 g solution,

(3) 51.3 g zinc nitrate solution containing 10.14 g Zinc per 100 g of solution.

The solution C is reacted with ammonium carbonate solution under the conditions described in Example 1, the pH is 8.5 and the excess alkalinity corresponds to 13.4 cm. The powder produced by drying is calcined

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one at 87O ° C, whereby a manganese / zinc ferrite is formed.

Example 4

Solution Ds
A mixture of:

{13 1767, 0 g ferrous sulfate stock solution with a content of 2.78 g iron per 100 solution,

(2) 106.9 g of manganese sulfate solution containing 10.05 g of manganese per 100 g of solution,

(3) 93.7 g zinc nitrate solution with a content of 13.9 g Zinc per 100 g solution,

(4) 7.9 qm calcium nitrate solution with a content of

3 28.0 g calcium nitrate tetrahydrate per 250 cm solution,

(5) 2.7 cm ³ titanosulphate solution (15%),

3
{6) 3.2 cm chromium sulfate solution with a content of

2 g chromium sulfate, 15 molecules of water, per 100 cm of solution.

Solution D is reacted with ammonium carbonate solution under the conditions described in Example 1, the pH being 8.7 and the excess alkalinity of the lye

"* 3
6.2 cm. The powder produced by drying is converted into a ferrite mass as described in Example 2 with the following properties: loss χ 10 at 100 KHZ 3.5; initial permeability 3052.

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Example 5

Solution egg

A mixture of:

(1) 1767.0 g of ferrous sulfate stock solution containing of 2.78 g of iron per 10 g of solution,

(2) 106.9 g of manganese sulphate solution with a content of 10.05 g of manganese per 100 g of solution,

(3) 93.7 g zinc nitrate solution containing 13.9 g Zinc per 100 g solution,

(4) 7.9 cm calcium nitrate solution with a content of 28.0 g calcium nitrate tetrahydrate per 250 cm solution,

(5) 2.7 cm ³ titanosulfate solution, 15% (w / v),

(6) 5 cm magnesium sulfate solution containing

10 g magnesium sulfate heptahydrate per 100 cm solution.

Solution E is reacted with ammonium carbonate solution under the conditions described in Example 1, the pH being 8.45 and the excess alkalinity corresponding to ^{11.1 cm 3.} The powder produced by drying is, as described in Example 1, converted into a ferrite mass (pressed into toroids at about 2137 kg / cm), which has the following properties: Loss χ 10 ⁶ at 100 KHZ 3.0; initial permeability 3203.

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Example 6

Solution E :

A mixture of:

(1) 1735.8 g ferrous sulfate ^ stock solution with a content of 2.83 g iron per 100 g solution,

(2) 106.9 g of manganese sulphate solution with a content of 10.05 g of manganese per 100 g of solution,

(3) 93.7 g zinc nitrate solution with a content of 13.9 g zinc per 100 g solution,

(4) 7.9 cm calcium nitrate solution with a content of 28.0 g calcium nitrate tetrahydrate per 250 cm solution,

(5) 2.7 cm ³ titanosulfate solution, 15% (w / v),

(6) 3.0 cm of cobalt sulphate solution containing 1.6 g of cobalt sulphate heptahydrate per 100 cm of solution.

Solution 0 is reacted with ammonium carbonate solution under the conditions described in Example 1, the pH value being 8.75 and the excess alkalinity corresponding to ^{15.1 cm 3.} The powder produced is calcined at 885 C and, as described in Example 1, converted (by pressing in toroids at 196Okg / cm ² ) into a ferrite mass with the following properties: Loss χ 10 ⁶ x 100 KHZ 3.6; initial permeability 4452.

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Example 7

Solution Q i

A mixture of

(1) 8709.5 g ferrous sulfate stock solution with a content of 2.82 g of iron per 100 g of solution,

(2) 588.7 g of manganese sulfate solution containing 9.13 g manganese per 100 g solution,

(3) 439.0 g zinc nitrate solution with a content of 14.65 g zinc per 100 g solution,

(4) 39.5 cm ³ calcium nitrate solution with a content of 28.0 g calcium nitrate tetrahydrate per 250 cm solution,

(5) 13.4 cm ^{3 of} titanosulfate solution (15%).

Solution 9 is reacted with ammonium carbonate solution to produce a first precipitate, which is produced and dried using the method described in Example 1, the pH being 8.20 and the excess alkalinity corresponding to 10 cm.

The predominant components in the dried powder

are present in the following proportions! Iron as Fe ₂ O ₃ 56.36%; Mn as MnO, 10.83%; and Zn as ZnO 10.65%. 50 g of the dry powder produced is then slurried with about 1 liter of deionized water and 3.39 g of zinc nitrate

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Stock solution added · Sufficient ammonium carbonate solution is added added to bring the pH of the slurry to about 8.00 The slurry is then stirred for about 30 minutes, filtered, washed and dried at 110 ° C.

The powder produced by the second precipitation is calcined one at 850 ° C and converts it as described in Example 2 through Pressing in toroids at about 2400 kg / cm) into a ferrite mass.

The experiment is repeated, 5.12 g, 5.8 g and 6.8 g of zinc nitrate solution, respectively, being added in the second precipitation stage.

The ferrites produced are those shown in Table I. Characteristics:

Table I.

Amount of ZnN03 added in the second precipitation stage

initial permeability

losses
χ 10 ⁶ at
100 KHZ

Hysterisis coefficient χ 1O ⁶

3.39 5.2 5.8 6.8

1984 3.9 0.8 2400 3.7 0.8 2410 4.3 0.8 2690 4.5 0.6

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Example 8

Solution Ht

A mixture of:

(1) 1649.0 g of ferrous sulfate stock solution containing on 2 # 83 g iron per 100 g solution,

(2) 106/9 g of manganese sulphate solution containing 10.05 g manganese per 100 g solution,

(3) 93.7 g zinc nitrate solution containing 13.9 g Zinc per 100 g solution,

(4) 7.9 cm calcium nitrate solution with a content of 37.5 g calcium nitrate tetrahydrate per 100 cm solution,

(5) 2.7 cm ^{3 of} titanosulfate solution, 15% (w / v).

The solution H is heated to about 70 ^° C. and then slowly added to ammonium carbonate solution (about 2.4 molar),

until the pH is 8.15. The excess alkalinity of the lye corresponds to 15 cm ^{3 of} 0.5 N HCl per 50 cm ^{3 of} filtered lye (using methyl orange as an indicator).

The precipitate is filtered off and washed free of sulfate ions with deionized water. The filter cake is then dried at about 100 ^° C. Using the dried powder, the following experiments are carried out »

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(A) 50 g of dried powder are mixed with 700 cm of water and 43.4 g of ferrous sulfate stock solution (containing 2.83 g of iron per 100 g of solution) slurried. Then you bet Add ammonium carbonate solution until pH is 8.05. The slurry is then stirred for about 30 minutes before it is filtered off and washed.

Das.Pulver is then calcined for 1 hour at 840 C in

Air. Then 10% of a 4% polyvinyl alcohol solution is added

and the powder is pre-pelletized at about 400 kg / cm.

These pellets are then broken up into granules of about 44 ha

2 see and then compress them into toroids at about 2500 kg / cm.

The toroids are finally densified by leaving them in a mixture of 2% oxygen and at 12500C for 2 hours 98% nitrogen sinters.

(B) 14.4 g of a ferric nitrate solution containing 8.5 g of iron per 100 g of solution v / earth for 50 g of the dried Sprayed on powder and mixed with it. The powder is then dried and calcined in air at 87O ° C for 1 hour, and toroids are generated as described above.

The properties of the ferrite masses produced in experiments (A) and (B) are given in Table II. These Properties would be improved if the manufacturing conditions be brought to an optimum.

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Tabel II losses
at 100 χ 1O ⁶
KHZ attempt initial
permeability 7.9 (A) 1794 12.1 (B) 1349 example 9

Solution it

A mixture of:

(1) 1735.8 g of ferrous sulfate stock solution containing of 2.83 g iron per 100 g solution,

(2) 106.9 g of manganese sulphate solution with a content of 10.05 g of manganese per 100 g of solution,

(3) 93.7 g zinc nitrate solution with a content of 13.9 g zinc per 100 g solution,

(4) 2.7 cm ^{3 of} titanosulfate solution, 15% (w / v).

A first precipitate is produced as described in Example $ , the pH being 7.9 and the excess alkalinity corresponding to 14.2 cm. 50 g of the dry powder produced are slurried with about 8OO cm of deionized water and 3.95 cm of a calcium nitrate stock solution (containing 37.5 g of calcium nitrate tetrahydrate per 100 cm of solution) is added. Sufficient ammonium carbonate solution is added to bring the pH of the slurry to about 8.0. Then stir the slurry

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30 minutes before you filtered it, washed and dried at ⁰ C IiO.

The dry powder produced is, as described in Example 1 (pressing in toroids at 1490 kg / cm), converted into a ferrite mass with the following properties: loss χ 10 ⁶ at 100 KHZ 11.4; initial permeability 1247.

Example 10

Solution J :

A mixture of:

(1) 338O.0 g of ferrous sulphate stock solution containing of 2.91 g iron per 100 g solution,

(2) 212.0 g of manganese sulfate solution containing 10.29 g manganese per 100 g solution,

(3) 172.0 g zinc nitrate solution with a content of 14.94 g zinc per 100 g solution.

A first precipitate is prepared and dried as described in Example B , the pH being 8.3 and the excess alkalinity corresponding to 11.4 cm.

50 g of the dry powder produced are then added 6, O cm of a calcium nitrate stock solution mixed, which Contains 7.5 g of calcium nitrate tetrahydrate per 100 cm of solution.

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The powder is then dried at 110 ^° C.

The dried powder produced is calcined for 1 hour at 850 ° C. in air and converted as described in Example 1

ben (by pressing in toroids at 2980 kg / cm) into a ferrite mass with the following properties: loss at 10 at 100 KHZ 7.5; initial permeability 1890.

Example Il

Solution K :

A mixture of:

(1) 1735.8 g ferrous sulphate stock solution with a content of 2.83 g iron per 100 g solution,

(2) 106.9 g of manganese sulphate solution with a content of 10.05 g of manganese per 100 g of solution,

(3) 93.7 g zinc nitrate solution containing 13.9 g

Zinc per 100 g solution,

(4) 7.9 cm calcium nitrate solution containing

3 37.5 g calcium nitrate tetrahydrate per 100 cm solution.

A first precipitate is prepared and dried as described in Example B , the excess alkalinity corresponding to ^{12.6 cm 3.}

0.296 g of titanium isopropoxide in dry dutanol, mixed

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one with 50 g of the dry powder. The powder is spread then out and leave it open overnight to allow it to dry and hydrolyze the organometallic compound.

The dry powder produced is calcined at 870 ° C. and, as described in Example 9 , is converted into a ferrite mass by pressing to form toroids at 1850 kg / cm.

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Claims (9)

Claims 1. Process for the production of ferrites by common Precipitation of a mixture which is an iron compound and a compound of at least one other metal has, from aqueous solution, and heating the co-precipitated mixture to form a ferrite, thereby characterized in that an aqueous solution of a soluble iron salt and a soluble salt of at least one other Metal, which is able to be precipitated from aqueous solution as a carbonate, for the purpose of precipitating a Reacts carbonate mixture with ammonium carbonate or bicarbonate. 2. The method according to claim 1, characterized in that the precipitated carbonate mixture is modified by an oxide or a precursor thereof is added to the carbonate mixture before heating to form the ferrite. 3. The method according to claim 1 or 2, characterized in that a manganese / zinc ferrite is produced. 4. The method according to claim 3, characterized in that the ferrite is an oxide of at least one of the elements zirconium, Has nickel, strontium, vanadium, chromium, copper, magnesium, silicon, barium, cobalt, calcium, titanium and aluminum in quantities, which are sufficient that up to 0.5% by weight of the element is incorporated in the ferrite. 209839/1 030 5. The method according to any one of the preceding claims, characterized in that the reaction is carried out at a pH value within the range from 8 to 8.4 » 6. The method according to one of the preceding claims, characterized in that the soluble salts used are nitrates, sulfates or chlorides. 7. The method according to any one of the preceding claims, characterized in that there is a solution of the soluble salts is added to a solution of ammonium carbonate and / or bicarbonate and that the resulting mixed solution Aged for one to 1 1/2 hours at a temperature of 20 to 50 ° C. 8. The method according to any one of the preceding claims, characterized in that the precipitated carbonate mixture prior to heating to form a ferrite at a temperature dries within the range of 100 to 120 C. 9. The method according to any one of the preceding claims, characterized in that the precipitated carbonate mixture dries before modifying. 1O, method according to one of the preceding claims, d & characterized in that the oxide precursor is a soluble 20983971030 Salt used, which can be precipitated with alkali, or a salt used which is to form a Oxyds decomposed. 209839/1030