JPS5917196B2 - Manufacturing method of metallic iron magnetic powder - Google Patents
Manufacturing method of metallic iron magnetic powderInfo
- Publication number
- JPS5917196B2 JPS5917196B2 JP56132336A JP13233681A JPS5917196B2 JP S5917196 B2 JPS5917196 B2 JP S5917196B2 JP 56132336 A JP56132336 A JP 56132336A JP 13233681 A JP13233681 A JP 13233681A JP S5917196 B2 JPS5917196 B2 JP S5917196B2
- Authority
- JP
- Japan
- Prior art keywords
- goethite
- aqueous
- magnetic powder
- ammonia
- metallic iron
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
- B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Hard Magnetic Materials (AREA)
- Paints Or Removers (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Magnetic Record Carriers (AREA)
Description
【発明の詳細な説明】
本発明は金属鉄磁性粉末の製造方法に関するものである
。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing metal ferromagnetic powder.
更に詳しくは、ゲータイトを還元性雰囲気中で加熱還元
して、針状の金属鉄磁性粉末を造る方法に関するもので
ある。磁気テープ、磁気記録体として有用な磁性粉末は
、従来γ−Ｆｅ２Ｏ３磁性粉末が主体であつたが、近年
ＶＴＲや高級オーディオ用の高密度磁気記録体が望まれ
るようになり、それにともなつて、数多くの強磁性粉末
が提案されている。More specifically, the present invention relates to a method for producing acicular ferromagnetic powder by heating and reducing goethite in a reducing atmosphere. The magnetic powder useful for magnetic tapes and magnetic recording bodies has traditionally been mainly γ-Fe2O3 magnetic powder, but in recent years, high-density magnetic recording bodies for VTRs and high-end audio have become desirable, and with that, A number of ferromagnetic powders have been proposed.
これらの中で特に酸化鉄もしくはオキシ水酸化鉄を主体
とする粉末を加熱還元して得られる金属鉄を主体とする
粉末は高い保磁力を有するものとして知られる。一般に
ゲータイトの製造方法は、硫酸第１鉄等の第１鉄塩の水
溶液に過剰の水酸化ナトリウムを加えて水酸化第１鉄水
溶液となし、これを酸化して得るのが普通である。これ
を加熱還元して針状晶： 金属鉄磁性粒子を得る。しか
しながら、この加熱工程で針状晶粒子間の焼結が起り易
い、この焼結を防止するためｓｉ、Ａｌ２Ｃｒなどを出
発原料のゲータイト粒子表面に事前にコーティングする
。特にＳｉをコーティングするのが一般的であり、０Ｓ
ｉ源としては水ガラスが多く用いられる。すなわち、水
ガラスをゲータイトの水懸濁液に所定量添加撹拌して、
しかる後、硫酸などでｐＨ３〜５にしてＳｉＯ２をゲー
タイト表面に被着させた後、該水懸濁液を濾過、洗浄乾
燥する。しかしながら、５ この方法は対、ｓｏ「など
の不純物の除去が困難で、加熱工程時の焼結の原因とな
り、還元も困難となる。従つて得られる金属鉄磁性粉末
の磁気特性は必ずしも好ましいものではない。本発明は
これら従来技術の欠点を改良して磁気０ 特性のすぐれ
た針状晶の金属鉄磁性粉末の製造方法を提供することを
目的とするものである。Among these, powders mainly composed of metallic iron obtained by thermal reduction of powders mainly composed of iron oxide or iron oxyhydroxide are known to have high coercive force. Generally, goethite is produced by adding excess sodium hydroxide to an aqueous solution of a ferrous salt such as ferrous sulfate to obtain an aqueous ferrous hydroxide solution, and then oxidizing the solution. This is heated and reduced to obtain acicular crystals: metallic iron magnetic particles. However, in this heating step, sintering between the needle-like crystal particles tends to occur. In order to prevent this sintering, the surfaces of the goethite particles, which are the starting materials, are coated in advance with Si, Al2Cr, or the like. In particular, it is common to coat with Si, and 0S
Water glass is often used as an i source. That is, a predetermined amount of water glass is added to an aqueous suspension of goethite and stirred.
Thereafter, the pH is adjusted to 3 to 5 using sulfuric acid or the like to deposit SiO2 on the goethite surface, and the aqueous suspension is filtered, washed and dried. However, in this method, it is difficult to remove impurities such as SO, which cause sintering during the heating process, and reduction is also difficult. Therefore, the magnetic properties of the obtained metallic iron magnetic powder are not necessarily favorable. The object of the present invention is to improve these drawbacks of the prior art and provide a method for producing acicular metal iron magnetic powder having excellent magnetic zero characteristics.
本発明の針状の金属鉄磁性粉末の製造方法は針状粒子か
らなるゲータイトの水懸濁液にケイ酸水溶液およびアン
モニアを加えて混合し、ｐＨ９．５〜５１０．５のゲー
タイト水分散液とし、つぎに該液に有機酸を加えてｐＨ
５〜７としてフロックを生成し、該フロックを分離し、
乾燥して処理されたゲータイトを得る。このゲータイト
を還元性雰囲気中４００〜６００℃で還元することから
なる。’０ 本発明におけるゲータイトの水懸濁液は針
状粒子からなるゲータイトの粉末を純水に懸濁させて充
分攪拌して得るか、または第１鉄塩水溶液にアルカリ水
溶液を加えて、水酸化第１鉄の沈澱物を生成し、これを
空気酸化した後濾過、水洗などの’５ 処理をして得た
ゲータイトの湿潤ケーキを純水に投入し撹拌して得られ
る。水懸濁液中のゲータイト濃度は通常２〜６％が適当
である。）クー
ケイ酸水溶液およびアンモニアを加える順序は特に問題
としないが、懸濁液のＰＨが９．５〜１０．５になるよ
うにアンモニアを加えて混合する。The method for producing the acicular metal iron magnetic powder of the present invention involves adding and mixing an aqueous silicic acid solution and ammonia to an aqueous suspension of goethite consisting of acicular particles to form an aqueous goethite dispersion having a pH of 9.5 to 510.5. , then add an organic acid to the solution to adjust the pH.
5 to 7 to generate flocs and separate the flocs,
Dry and processed goethite is obtained. This process consists of reducing this goethite at 400 to 600°C in a reducing atmosphere. '0 The aqueous suspension of goethite in the present invention can be obtained by suspending goethite powder consisting of acicular particles in pure water and thoroughly stirring it, or by adding an alkaline aqueous solution to a ferrous salt aqueous solution and hydrating it. It is obtained by generating a ferrous precipitate, oxidizing it in air, and then subjecting it to '5 treatments such as filtration and washing with water. A wet cake of goethite is then poured into pure water and stirred. The appropriate goethite concentration in the aqueous suspension is usually 2 to 6%. ) The order in which the cousilicic acid aqueous solution and ammonia are added does not matter, but ammonia is added and mixed so that the pH of the suspension becomes 9.5 to 10.5.
この添加混合によつて懸濁液の粘度は著しく低下し、ゲ
ータイト個々の粒子が完全に分散されてその粒子表面に
Ｓｉて均一に被着されたゲータイト水分散液が得られる
。本発明におけるケイ酸水溶液とアンモニアの添加は、
Ｓｉの被着効率（被着Ｓｉ量／添加Ｓｉ量）を高くする
ことが出来、またＳｉ被着の再現性がよく、Ｓｉ被着量
のコントロールを容易にする効果がある。本発明のアン
モニアに代えて、水酸化ナトリウム、水酸化カリウムな
どを使用すると、焼結を促進し、還元を阻害する。また
、ケイ酸水溶液に代えて、ケイ酸ナトリウム、水ガラス
などを使用しても同様に焼結、還元率低下を示し、本発
明の目的を達成することができない。本発明に使用する
ケイ酸水溶液とはオルトケイ酸、Ｈ４ＳｉＯ４など各種
ケイ酸水溶液、水溶液状シリカゾルあるいは、アンモニ
アで安定化された水溶液状シリカゾルをいう。By this addition and mixing, the viscosity of the suspension is significantly reduced, and an aqueous goethite dispersion in which individual goethite particles are completely dispersed and Si is uniformly deposited on the particle surfaces is obtained. The addition of silicic acid aqueous solution and ammonia in the present invention is as follows:
The Si deposition efficiency (deposited Si amount/added Si amount) can be increased, the Si deposition has good reproducibility, and the Si deposition amount can be easily controlled. When sodium hydroxide, potassium hydroxide, etc. are used in place of ammonia in the present invention, sintering is promoted and reduction is inhibited. Furthermore, even if sodium silicate, water glass, or the like is used in place of the silicic acid aqueous solution, the sintering and reduction rate similarly decrease, making it impossible to achieve the object of the present invention. The silicic acid aqueous solution used in the present invention refers to various silicic acid aqueous solutions such as orthosilicic acid and H4SiO4, aqueous silica sol, or aqueous silica sol stabilized with ammonia.
これら水溶液またはゾルのＳｉ濃度は通常０．０１〜１
０％である。本発明におけるアンモニアの添加は、アン
モニア水の添加、アンモニアガスの吹込みなど如何なる
方法でもよく、懸濁液のＰＨが９．５〜１０．５になる
ように加えればよい。ゲータイト水分散液は分散性が著
しくよいため通常の手段では固液の分離ができないが、
有機酸を加えて中和しＰＨを５〜７にすることによつて
フロツクを生成し、分離を容易にすることができる。The Si concentration of these aqueous solutions or sols is usually 0.01 to 1
It is 0%. Ammonia may be added in the present invention by any method such as adding ammonia water or blowing ammonia gas, and may be added so that the pH of the suspension becomes 9.5 to 10.5. Goethite aqueous dispersion has extremely good dispersibility, so solid-liquid separation cannot be done by normal means.
By adding an organic acid to neutralize and bring the pH to 5 to 7, a floc can be generated to facilitate separation.
フロツクの分離は如何なる方法でもよいが通常淵別され
る。有機酸としては、クエン酸、シユウ酸、酢酸等いず
れでもよいが、アンモニウム塩および酸の沸点からして
、工業的には酢酸が有利に使用できる。酢酸を用いた場
合は戸別後は１２０〜１２５℃で乾燥することにより不
純物が少なく均一にＳｉの被着されたゲータイトが得ら
れる。本発明の有機酸にかえて、硫酸リン酸等無機酸を
使用すると、陰イオンの除去が困難で、焼結、還元率低
下を起し、磁気特性を低下させる原因となる。本発明の
処理されたゲータイトは水素気流中で還元して針状の金
属鉄磁性粉末が得られる。還元温度は４００〜６００℃
である。本発明の不純物のない処理されたゲータイトを
使用することにより、従来の還元温度より高温度での還
元に耐えることができるようになり、磁気特性のすぐれ
たものが製造できるようになつた。Although the flocs may be separated by any method, they are usually separated. The organic acid may be any of citric acid, oxalic acid, acetic acid, etc., but acetic acid can be advantageously used industrially in view of the ammonium salt and the boiling point of the acid. When acetic acid is used, by drying at 120 to 125°C after separation, goethite with few impurities and uniformly coated with Si can be obtained. If an inorganic acid such as sulfuric acid or phosphoric acid is used instead of the organic acid of the present invention, it is difficult to remove anions, causing sintering and a reduction in the reduction rate, resulting in a decrease in magnetic properties. The treated goethite of the present invention is reduced in a hydrogen stream to obtain acicular metallic iron magnetic powder. Reduction temperature is 400-600℃
It is. By using the impurity-free treated goethite of the present invention, it has become possible to withstand reduction at higher temperatures than conventional reduction temperatures, and it has become possible to produce products with excellent magnetic properties.
本発明の製造法の特徴は、使用するゲータイトが、本発
明特有の処理により、不純物を殆んど含まないことにあ
る。本発明はアンモニアとケイ酸水溶液を使用すること
によりゲータイト個々の粒子が完全に分散され、Ｓｉが
均一に被着した液が得られるが、本発明の不純物のない
理由は、該分散液を中和する際に例えば酢酸を用いるこ
とにより生成する塩、すなわち酢酸アンモニアと残留す
る酢酸が１２０〜１２５℃の乾燥温度で分解蒸発して除
去されることである。A feature of the production method of the present invention is that the goethite used contains almost no impurities due to the treatment unique to the present invention. In the present invention, individual goethite particles are completely dispersed by using an ammonia and silicic acid aqueous solution, and a liquid on which Si is uniformly coated can be obtained. For example, by using acetic acid during the mixing, the salt produced, that is, ammonia acetate and the remaining acetic acid are removed by decomposition and evaporation at a drying temperature of 120 to 125°C.
すなわち従来の方法のように焼結の原因となるＮｔ，Ｓ
σ嘲，還元を抑制するＰＯ→等が被着しないためと考え
られる。本発明の方法はゲータイトへのＳｉの被着のコ
ントロールが容易であり、Ｓｉ被着効率が９０７０以上
であり、均一に被着するため焼結防止効果は著しく向上
する。また、本発明の金属鉄磁性粉は磁性塗料への分散
性がきわめて良好である。以下実施例、比較例にて本発
明を説明する。In other words, unlike conventional methods, Nt and S, which cause sintering, are
This is thought to be due to the fact that sigma, PO→, etc. that suppress reduction are not deposited. In the method of the present invention, it is easy to control the deposition of Si on goethite, the Si deposition efficiency is 9070 or more, and the Si deposition is uniformly deposited, so the sintering prevention effect is significantly improved. Furthermore, the metal iron magnetic powder of the present invention has extremely good dispersibility in magnetic paints. The present invention will be explained below with reference to Examples and Comparative Examples.
実施例 １〜１０ゲータイトの湿潤ケーキ（乾燥基準３
３０ｆ！）を純水６６００９の中に投入して懸濁させた
。Examples 1-10 Wet cake of goethite (dry standard 3
30f! ) was put into pure water 66009 and suspended.
これに２８％アンモニア水溶液８ｍ１を加えてＰＨｌＯ
３とした。スラリー粘度は低下した。さらにオルトケイ
酸水溶液（Ｓｉ濃度１％）を所定量加えて混合して、ス
ラリー粘度がさらに低下したゲータイト水分散液を得た
。充分撹拌してＳｉを均一被着させた後、この液に９９
．５７０酢酸６ｍ１を加え、ＰＨ６．５としてフロツク
を生成させた。該フロツクを淵別し、１２０〜１２５℃
にて乾燥して表１に示すような処理された乾燥ゲータイ
トが得られた。この処理された乾燥ゲータイト３１０９
を水素流量１０１／分、１２時間、を表１に示す所定温
度条件でロータリー式還元炉を用いて、還元し針状の金
属鉄磁性粉末を得た。その特性値を表１に示した。比較
例 １〜８
比較例は、実施例にてアンモニア及び酢酸を用いなかつ
た。Add 8 ml of 28% ammonia aqueous solution to this and
It was set as 3. Slurry viscosity decreased. Furthermore, a predetermined amount of orthosilicic acid aqueous solution (Si concentration 1%) was added and mixed to obtain a goethite aqueous dispersion in which the slurry viscosity was further reduced. After sufficiently stirring to coat Si uniformly, add 99% to this solution.
．． 6 ml of 570 acetic acid was added to adjust the pH to 6.5 and form a floc. Separate the floc and heat at 120-125°C.
The dried goethite treated as shown in Table 1 was obtained. This treated dry goethite 3109
was reduced using a rotary reduction furnace at a hydrogen flow rate of 101/min for 12 hours under the predetermined temperature conditions shown in Table 1 to obtain needle-shaped metallic iron magnetic powder. The characteristic values are shown in Table 1. Comparative Examples 1 to 8 In Comparative Examples, ammonia and acetic acid were not used in the Examples.
比較例３〜８はＳｉ源として、シリカゾル、２号水ガラ
ス水溶液、ケイ酸水溶液、中和剤として酢酸、硫酸、リ
ン酸を用いて各種組合せのもとにＳｉをゲータイトに被
着させた以外は
実施例と全く同一の操作を行なつた。In Comparative Examples 3 to 8, Si was deposited on goethite in various combinations using silica sol, No. 2 water glass aqueous solution, silicic acid aqueous solution as a Si source, and acetic acid, sulfuric acid, and phosphoric acid as neutralizing agents. The same operation as in the example was performed.
Claims (1)
金属鉄磁性粉末を製造するに際して、ゲータイトの水懸
濁液にケイ酸水溶液およびアンモニアを加えて混合し、
ｐＨを９．５〜１０．５のゲータイト水分散液とし、つ
ぎに該液に有機酸を加えてｐＨを５〜７として、フロッ
クを生成し該フロックを分離乾燥して得られる処理され
たゲータイトを使用することを特徴とする針状の金属鉄
磁性粉末の製造方法。1. When producing acicular metallic iron magnetic powder by thermally reducing goethite in a reducing atmosphere, add and mix an aqueous silicic acid solution and ammonia to an aqueous suspension of goethite,
Treated goethite obtained by preparing an aqueous goethite dispersion with a pH of 9.5 to 10.5, then adding an organic acid to the solution to adjust the pH to 5 to 7 to form flocs, and separating and drying the flocs. A method for producing acicular ferromagnetic powder.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56132336A JPS5917196B2 (en) | 1981-08-24 | 1981-08-24 | Manufacturing method of metallic iron magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56132336A JPS5917196B2 (en) | 1981-08-24 | 1981-08-24 | Manufacturing method of metallic iron magnetic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5834106A JPS5834106A (en) | 1983-02-28 |
| JPS5917196B2 true JPS5917196B2 (en) | 1984-04-19 |
Family
ID=15078941
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56132336A Expired JPS5917196B2 (en) | 1981-08-24 | 1981-08-24 | Manufacturing method of metallic iron magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5917196B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60149790U (en) * | 1984-03-14 | 1985-10-04 | 三菱重工業株式会社 | robot arm |
| JPH03239495A (en) * | 1990-02-15 | 1991-10-25 | Mitsubishi Electric Corp | Wrist unit structure in articulated robot |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110014165B (en) * | 2019-05-23 | 2020-07-17 | 西北有色金属研究院 | Preparation method of high-purity micron-sized spherical molybdenum powder |
-
1981
- 1981-08-24 JP JP56132336A patent/JPS5917196B2/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60149790U (en) * | 1984-03-14 | 1985-10-04 | 三菱重工業株式会社 | robot arm |
| JPH03239495A (en) * | 1990-02-15 | 1991-10-25 | Mitsubishi Electric Corp | Wrist unit structure in articulated robot |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5834106A (en) | 1983-02-28 |
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