JPS5948766B2 - Goethite manufacturing method - Google Patents

Description

【発明の詳細な説明】 本発明はゲータイト、特に磁気記録用ガンマ酸化第二鉄
の素材として好適なゲータイトの製法に関するものであ
り、軸比が大きく、粒度分布がシャープで、常法で環元
酸化を行つたときに、保磁力が大きい価を示すガンマ酸
化第二鉄が得られるようなゲータイトを製造することを
目的とする。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing goethite, which is suitable as a material for gamma ferric oxide for magnetic recording. The object of the present invention is to produce goethite such that when oxidized, gamma ferric oxide having a high coercive force can be obtained.

ガンマ酸化第二鉄の原料であるゲータイトの製法は現在
、結晶核となるゲータイトの微結晶（シート）の存在の
もとで第一鉄塩水溶液を４０〜７５℃に保ち、酸化剤と
しての空気の送入を行い、それによつて遊離してくる酸
を中和するためにアルカリ剤、例へばアンモニアガスを
、反応系のＰＨが３〜５の間の予め設定したＰＨを保つ
様な割合で連続的に供給することによつて、前記シート
上にゲータイトを析出成長させる酸性法と、第一鉄塩の
水溶液に当量以上のアルカリ金属の水酸化物の水溶液を
加え、ＰＨが１１〜１３或はそれ以上の高アルカリ側で
適当な温度のもとで空気送入を行うことによつてゲータ
イトを析出させるアルカリ法、との２つの方法に大別で
きる。酸性法は、結晶核の生成条件が適当であれば粒度
分布がシャープで均一なゲータイトを得ることができる
特徴があり、アルカリ法は、軸比が大きく保磁力の価の
高いガンマ酸化第二鉄を生ずる様なゲータイトが得られ
る特徴がある。The current manufacturing method for goethite, which is the raw material for gamma ferric oxide, is to maintain an aqueous ferrous salt solution at 40 to 75°C in the presence of goethite microcrystals (sheets) that serve as crystal nuclei, and to use air as an oxidizing agent. In order to neutralize the acid liberated by this, an alkali agent, for example, ammonia gas, is continuously introduced at a rate that maintains the pH of the reaction system at a preset pH between 3 and 5. An acidic method in which goethite is precipitated and grown on the sheet by supplying an aqueous solution of ferrous salt, and an aqueous solution of an alkali metal hydroxide in an amount equal to or more than an equivalent amount is added to an aqueous solution of a ferrous salt until the pH is 11 to 13 or It can be roughly divided into two methods: the alkaline method, in which goethite is precipitated by introducing air at an appropriate temperature on the higher alkaline side; and the alkaline method. The acidic method is characterized by being able to obtain goethite with a sharp and uniform particle size distribution if the conditions for crystal nucleation are appropriate, while the alkaline method produces gamma ferric oxide with a large axial ratio and high coercive force. It is characterized by the ability to obtain goethite that produces .

本発明者等は、粒度分布がシャープでよく揃つておりし
かも軸比が大きいゲータイトを得るために数多くの実験
と検討を行つた結果、特定の限られた条件のもとで、Ｐ
Ｈ７よりも酸性側で生成させたゲータイト構造をもつシ
ートの存在で、硫酸第一鉄或は塩化第一鉄水溶液に、鉄
塩の当量以上のアルカリ金属の水酸化物の水溶液を加え
てＰＨ１２以上に調整し、４００〜７５℃の間に設定し
た適切な温度のもとで空気を送入すること、充分撹拌混
合された状態を保つこと、によつて前記シート上に高ア
ルカリ側でゲータイトを析出成長させるという全く新し
い考え方に基づく技術的に容易な方法に到達したもので
ある。本発明によるゲータイトは粒度分布がシャープで
よく揃つており、軸比が大きい特徴があり、更に本発明
に基づいてシートの成長工程で、アルカリ金属の水酸化
物の水溶液例へば水酸化ナトリウムの水溶液に、燐酸塩
或は硅酸塩或は燐酸塩と硅酸塩の混合物を微量添加して
おくと前記特徴が助長され、これから得られるガンマ酸
化鉄の保磁力が著しく向上することを発見した。先ずシ
ート生成工程について説明する。硫酸第一鉄或は塩化第
一鉄の水溶液の濃度は、１１当り、Ｆｅとして２０９〜
６０９の範囲が好ましいが、これよりも低い第一鉄塩濃
度でシート生成反応を行い、成長反応に移る前に第一鉄
塩を補充してもかまわないしこれよりも高い濃度でシー
ト生成反応を行い、シートの成長工程で濃度を下げても
かまわない。The present inventors conducted numerous experiments and studies in order to obtain goethite with a sharp and uniform particle size distribution and a large axial ratio.
Due to the presence of a sheet with a goethite structure produced on the more acidic side than H7, an aqueous solution of an alkali metal hydroxide in an amount equivalent to or more than the iron salt is added to an aqueous solution of ferrous sulfate or ferrous chloride to raise the pH to 12 or higher. Goethite is added to the sheet on the high alkaline side by blowing air at an appropriate temperature between 400 and 75 degrees Celsius, and keeping the mixture well stirred. This is a technically easy method based on a completely new concept of precipitation growth. The goethite according to the present invention has a sharp and well-uniform particle size distribution, and is characterized by a large axial ratio.Furthermore, in the sheet growth process based on the present invention, an aqueous solution of an alkali metal hydroxide, for example, an aqueous solution of sodium hydroxide, is used. It has been discovered that adding a small amount of phosphate, silicate, or a mixture of phosphate and silicate promotes the above characteristics and significantly improves the coercive force of gamma iron oxide obtained therefrom. First, the sheet generation process will be explained. The concentration of the aqueous solution of ferrous sulfate or ferrous chloride is 209 to 11 as Fe.
The range of 609 is preferable, but the sheet formation reaction may be performed at a ferrous salt concentration lower than this, and the ferrous salt may be replenished before proceeding to the growth reaction, or the sheet formation reaction may be performed at a concentration higher than this. The concentration may be lowered during the sheet growth process.

シートを生成させるための第一鉄塩の中和率は第一鉄塩
の５〜５０％の範囲が好ましくこの範囲内で最初の第一
鉄塩濃度を低くし中和率を高くとり、低温でシートを生
成させてもよいし更に第一鉄塩を補充して単位容積当り
の収量増をはかることもできる。最初の第一鉄塩濃度を
高めにしておき、中和率を若干低くとつて比較的高温で
シートを生成させることもできるが、５％より低い中和
率ではシートの効果はほとんどなく、５０％以上では鉄
塩の濃度を下げないとシート生成時の粒度が高くなり作
業性が悪くなリメリツトが低い。シート生成温度は３０
〜６５℃が好ましく、３０℃以下の温度に保持すること
は夏季は困難な場合があり、又シート生成に時間がかか
る他ゲータイト以外の結晶構造をもつ生成物が混在して
くるおそれがある。６５℃以上になるとシートの粒子が
粗大化するおそれがありマグネタイトが生成する可能性
もあるからシート生成工程の温度は３０）〜６５℃の間
であるべきである。The neutralization rate of ferrous salt for forming a sheet is preferably in the range of 5 to 50% of the ferrous salt, within this range, the initial ferrous salt concentration is low, the neutralization rate is high, and the A sheet may be produced by using ferrous salt, or a ferrous salt may be added to increase the yield per unit volume. It is possible to generate a sheet at a relatively high temperature by keeping the initial ferrous salt concentration high and the neutralization rate slightly lower, but if the neutralization rate is lower than 5%, the sheet has little effect, and 50% % or more, unless the concentration of iron salt is lowered, the grain size during sheet production will increase, resulting in poor workability and low merit. Sheet generation temperature is 30
The temperature is preferably 65° C. to 30° C., and it may be difficult to maintain the temperature below 30° C. in summer, and it may take a long time to form a sheet, and products having crystal structures other than goethite may be mixed in. If the temperature exceeds 65°C, the particles of the sheet may become coarse and magnetite may be generated, so the temperature of the sheet forming process should be between 30°C and 65°C.

中和剤としてはアルカリ金属の炭酸塩、或は水酸化物が
好ましいが炭酸塩を用いる方が、水酸化物を用いるより
もシート生成工程の粘度を低く維持できるため作業性が
よく粒度分布のシヤープなシートを得られやすい。他の
アルカリ剤例へばアンモニアで中和した場合もシートは
生成するがシート成長工程で高アルカリ側に移つたとき
にアンモニアが遊離するから好ましくない。アルカリ土
類金属の炭酸塩例へばカルシウムの炭酸塩或は水酸化物
と塩化第一鉄の組合せでもシートは得られるがシート成
長工程で炭酸カルシウムが析出したり微量添加物として
加える燐酸塩や珪酸塩と結びつくから好ましくない。粒
度分布がシヤープでよく揃つており針状比が大きいゲー
タイトを得るためにはシートの粒度分布がシヤープであ
り軸比も大きいことが重要である。Carbonates or hydroxides of alkali metals are preferable as neutralizing agents, but using carbonates allows for better workability and improves particle size distribution because the viscosity can be maintained lower during the sheet production process than when using hydroxides. Easy to get a sharp sheet. As another example of an alkaline agent, a sheet can be formed even when neutralized with ammonia, but this is not preferable because ammonia is liberated when the process moves to a highly alkaline side in the sheet growth process. Carbonates of alkaline earth metals For example, sheets can be obtained by combining calcium carbonates or hydroxides with ferrous chloride, but calcium carbonate precipitates during the sheet growth process, or phosphates and silicates are added as trace additives. This is not desirable because it is associated with In order to obtain goethite with a sharp and uniform particle size distribution and a high acicular ratio, it is important that the sheet has a sharp particle size distribution and a large axial ratio.

シートの生成条件について数多くの試験検討を行つた結
果、第一鉄塩水溶液にアルカリ金属の炭酸塩の水溶液或
はアルカリ金属の水酸化物の水溶液を加えて生成した炭
酸第一鉄或は水酸化第一鉄を主とする沈澱を熟成させる
と望ましくないシートが生成することが判つた。すなわ
ち第一鉄塩水溶液に炭酸ナトリウム水溶液、水酸化ナト
リウム水溶液を長時間かけて加えたり、或は短時間に加
えた場合でも酸化剤としての空気の送入を始める前に長
時間撹拌を続けることは沈澱を熟成させる結果になるこ
と、熟成させた沈澱から得られるシートは、Ｘ線回析に
よる構造は好ましいシートと全く区別できないゲータイ
ト構造を示すが電子顕微鏡による観察では好ましいシー
トよりも軸比が小さくなること、このようなシートを本
発明方法に従つて成長させて得たゲータイトを常法で還
元、酸化して生成したガンマ酸化鉄の保磁力は熟成時間
に応じて低下することが判つた。表１は熟成時間がガン
マ酸化鉄の保磁力に及ぼす影響をまとめたもので、第一
鉄塩水溶液にアルカリ水溶液を加えて直ちに空気送入を
始めた実施例１に比べて、アルカリ水溶液を加えてから
３０分間撹拌した後空気送入を始めた比較例４は保磁力
が５０エルステツド低下している。As a result of numerous tests and studies on sheet formation conditions, we found that ferrous carbonate or hydroxide produced by adding an aqueous solution of alkali metal carbonate or aqueous solution of alkali metal hydroxide to an aqueous solution of ferrous salt. It has been found that aging of ferrous-based precipitates produces undesirable sheets. In other words, if a sodium carbonate aqueous solution or a sodium hydroxide aqueous solution is added to a ferrous salt aqueous solution over a long period of time, or even if it is added in a short period of time, stirring must be continued for a long time before starting to introduce air as an oxidizing agent. The sheet obtained from the aged precipitate shows a goethite structure that is completely indistinguishable from the preferred sheet by X-ray diffraction, but when observed by electron microscopy, the axial ratio is lower than the preferred sheet. It was found that the coercive force of gamma iron oxide, which is produced by reducing and oxidizing goethite obtained by growing such a sheet according to the method of the present invention in a conventional manner, decreases with aging time. . Table 1 summarizes the effect of aging time on the coercive force of gamma iron oxide. In Comparative Example 4, in which air supply was started after stirring for 30 minutes, the coercive force decreased by 50 oersteds.

このような理由から第一鉄沈澱の熟成時間は３０分未満
でなければならない。熟成時間を短くする手段として第
一鉄塩水溶液の温度とアルカリの水溶液の温度をシート
生成温度と同じか或は近い温度にしておくこと、径の大
きい配管を行うこと、反応槽に内筒を設けることなどが
考えられる。第一鉄塩として、硫酸第一鉄を用いる場合
は問題ないが塩化第一鉄を用いるとゲータイト（アルフ
アオキシ水酸化鉄）のほかにベータオキシ水酸化鉄やガ
ンマオキシ水酸化鉄を生成しやすい。For this reason, the aging time of the ferrous precipitate should be less than 30 minutes. As a means to shorten the aging time, it is necessary to keep the temperature of the ferrous salt aqueous solution and the aqueous alkali solution at the same or close to the sheet formation temperature, to use piping with a large diameter, and to install an inner cylinder in the reaction tank. It is conceivable to set one up. There is no problem if ferrous sulfate is used as the ferrous salt, but if ferrous chloride is used, beta-ferric oxyhydroxide and gamma-ferric oxyhydroxide are likely to be produced in addition to goethite (alpha-oxyferric hydroxide).

これらゲータイト以外のオキシ水酸化鉄が副成するとシ
ートの粒度分布が巾広くなりそれを成長させて得たゲー
タイトも粒度分布がプロードになる。本発明者等はゲー
タイト以外のオキシ水酸化鉄の生成を抑制するため種々
の添加物の効果を検討した結果硫酸第一鉄が好ましいこ
とを見出した。すなわち塩化第一鉄の水溶液に硫酸第一
鉄を適当な量溶解して本発明方法に従つてシートを生成
させるとゲータイト以外のオキシ水酸化鉄の生成が抑制
され、Ｘ線回析によつてゲータイト構造を示す粒度分布
がシヤープなシートが生成する。このようにして生成し
たシートを本発明方法に従つて成長させると粒度分布が
シヤープで、常法で還元、酸化したときに高い保磁力を
示すガンマ酸化鉄を生ずるようなゲータイトが得られる
。（実帷例１１参照）もちろん硫酸第一鉄以外の前記ベ
ータオキシ水酸化鉄、ガンマオキシ水酸化鉄生成抑制剤
を添加しても本発明の範囲を逸脱するものではない。次
にシート成長工程について説明する。今までのべて来た
様ほ、本発明方法に従つてシート生成工程で得られた軸
比が大きく粒度分布がシヤープなシートを含む懸濁液の
温度を４５〜７５℃の間の予め定めた温度に保ち、撹拌
機或は少量の空気の送入或は不活性ガスの送入によつて
撹拌された状態を保ち、シート懸濁液中に残存している
第一鉄塩の全てを中和するのに必要な量以上の水酸化ナ
トリウム、或は水酸化カリウムの水溶液を加え、酸化を
できるだけ避けながら、充分に混合する。When these iron oxyhydroxides other than goethite are formed as sub-formers, the particle size distribution of the sheet becomes wide, and the goethite obtained by growing it also has a broad particle size distribution. The present inventors investigated the effects of various additives for suppressing the production of iron oxyhydroxide other than goethite, and found that ferrous sulfate is preferable. That is, when a suitable amount of ferrous sulfate is dissolved in an aqueous solution of ferrous chloride and a sheet is produced according to the method of the present invention, the production of iron oxyhydroxide other than goethite is suppressed, and X-ray diffraction shows that A sheet with a sharp particle size distribution exhibiting a goethite structure is produced. When the sheet thus produced is grown according to the method of the present invention, goethite is obtained which has a sharp particle size distribution and produces gamma iron oxide having a high coercive force when reduced and oxidized by conventional methods. (See Practical Example 11) Of course, the addition of the beta-iron oxyhydroxide and gamma-iron oxyhydroxide production inhibitors other than ferrous sulfate does not depart from the scope of the present invention. Next, the sheet growth process will be explained. As described above, the temperature of the suspension containing the sheets with a large axial ratio and a sharp particle size distribution obtained in the sheet production process according to the method of the present invention is preset between 45 and 75°C. All remaining ferrous salts in the sheet suspension were removed by keeping the sheet at a temperature of Add an aqueous solution of sodium hydroxide or potassium hydroxide in an amount greater than that required for neutralization, and mix thoroughly while avoiding oxidation as much as possible.

アルカリ金属の水酸化物の量は、シート懸濁液中の第一
鉄塩を全て中和するのに必要な量よりも多くないとマグ
ネタイトが生成してくるから、生成する水酸化第一鉄と
シートの混合懸濁液のＰＨ値で１２以上を示すまで加え
なければならない。このようにして得たシートと水酸化
第一鉄の混合物懸濁液をなるべく酸化を抑えて、例へば
撹拌機のみ或は窒素ガスの送入等によつてよく混合する
。次で、この均一な懸濁液を４０〜７５℃に保ちながら
空気を送入する。生成したばかりの水酸化第一鉄とシー
トの混合懸濁液は粘度が低いが空気の送入を行うと次第
に粘度が高くなつてくる。前に述べたような熟成を長時
間、例へば３０分行つてから生成したシート懸濁液を当
量以上の水酸化ナトリウム水溶液で中和して生成した水
酸化第一鉄、とシートの混合懸濁液に空気送入を行つた
場合は粘度の上昇は極めて小さい。又シートが正常に生
成された場合でもその懸濁液に加える当量以上のアルカ
リ金属の水酸化物の水溶液に珪酸塩、例へば珪酸ナトリ
ウムを添加溶解しておいた場合にも珪酸塩の量がＳｉ／
Ｆｅで１／１００近辺からそれ以上添加されていると粘
度の上昇は極めて低い。りん酸塩、例へばヘキサメタ燐
酸ナトリウムを溶解したアルカリ金属の水酸化物の水溶
液を鉄塩の当量以上加えて同様に空気送入を行つた場合
は粘度の上昇が見られる。この様にして高アルカリ側で
シートと水酸化第一鉄の混合物懸濁液に適当な温度で空
気を送入し続けると、水酸化第一鉄が溶解しシート上に
ゲータイトが析出し成長してくる。If the amount of alkali metal hydroxide is not greater than the amount required to neutralize all the ferrous salts in the sheet suspension, magnetite will form; and the sheet must be added until the pH value of the mixed suspension shows 12 or more. The suspension of the mixture of the sheet and ferrous hydroxide obtained in this manner is thoroughly mixed by suppressing oxidation as much as possible, for example, by using only a stirrer or by supplying nitrogen gas. Next, air is introduced into this uniform suspension while maintaining it at a temperature of 40 to 75°C. The mixed suspension of ferrous hydroxide and sheet that has just been produced has a low viscosity, but as air is introduced, the viscosity gradually increases. A mixed suspension of sheets and ferrous hydroxide, which is produced by neutralizing the sheet suspension produced after the above-mentioned aging for a long time, for example 30 minutes, with an equivalent or more aqueous sodium hydroxide solution. When air is introduced, the increase in viscosity is extremely small. Furthermore, even if a sheet is normally produced, if a silicate, for example, sodium silicate, is added and dissolved in an aqueous solution of an alkali metal hydroxide in an amount equal to or more than the amount added to the suspension, the amount of silicate is /
When Fe is added from around 1/100 or more, the increase in viscosity is extremely low. If an aqueous solution of an alkali metal hydroxide in which a phosphate, for example sodium hexametaphosphate, is dissolved is added in an amount equivalent to or more than the iron salt and air is introduced in the same manner, an increase in viscosity is observed. In this way, when air is continuously introduced into the suspension of the sheet and ferrous hydroxide mixture at an appropriate temperature on the highly alkaline side, the ferrous hydroxide dissolves and goethite precipitates and grows on the sheet. It's coming.

全ての水酸化第一鉄が消失しゲータイトの成長が終つた
ら反応を止め生成物を淵過、水洗６乾燥、粉砕する。前
に述べた様に、シート成長工程でアルカリ金属の水酸化
物の水溶液に、ヘキサメタ燐酸ナトリウムのような燐酸
塩或はメタ珪酸ナトリウムのような珪酸塩を微量溶解し
ておくと、最終的に生成するゲータイトの粒度分布がよ
りシヤープになり、軸比が大きくなる。又このようにし
て得たゲータイトを常法で還元してマグネタイトとし、
次で酸化して生成したガンマ酸化鉄の保磁力が向上する
。この効果は、表２にまとめた様にＰ／Ｆｅ又はＳｌ／
Ｆｅ或は（Ｐ＋ＳＩ）／Ｆｅが２／１００を越えると低
下してくる。又２／１００を越えると成長反応を終了し
たゲータイトの懸濁液の涙過速度が急速に低下してくる
。このような理由から添加量の上限を２／１００とした
。実施例 １ 硫酸第一鉄７水塩７８１ｆ！を水２６３０ｍ１に溶解し
４０℃に加熱してある反応槽に移した。When all the ferrous hydroxide has disappeared and the growth of goethite has finished, the reaction is stopped and the product is filtered, washed with water, dried, and crushed. As mentioned earlier, if a small amount of phosphate such as sodium hexametaphosphate or silicate such as sodium metasilicate is dissolved in an aqueous solution of alkali metal hydroxide during the sheet growth process, the final The particle size distribution of the produced goethite becomes sharper and the axial ratio increases. In addition, the goethite obtained in this way is reduced to magnetite by a conventional method,
The coercive force of gamma iron oxide produced by oxidation is improved in the following step. As summarized in Table 2, this effect can be seen in P/Fe or Sl/
When Fe or (P+SI)/Fe exceeds 2/100, it decreases. Moreover, when the ratio exceeds 2/100, the tear velocity of the goethite suspension that has completed the growth reaction rapidly decreases. For this reason, the upper limit of the amount added was set at 2/100. Example 1 Ferrous sulfate heptahydrate 781f! was dissolved in 2630 ml of water and transferred to a reaction tank heated to 40°C.

これに空気５．５ｍ３／時を送入しながら無水炭酸ソー
ダ８９．３９を水１５００ｍ１に溶解して４０℃に加熱
した溶液を２０秒かけて加えた。白色の沈澱が生じ急速
に青色、濃青色、青緑色を経て９０分後に黄土色になつ
た。温度を５０℃に上げ、生成したシートをサンプリン
グした。懸濁液のＰＨは３３を示し電子顕微鏡観察の結
果長さ０．５ミクロン、巾０．０３〜０．０５ミクロン
の針状結晶が見られ、Ｘ線回析でゲータイト構造をもつ
ことが確認できた。このシート懸濁液に水酸化ナトリウ
ム２７５．３９を水４７２０ｍ１に溶解し５０℃に加熱
した溶液を２０秒かけて加え、空気を３ｍ゛／時の割合
で送入した。１時間後から粘度が上りはじめ緑色をおび
た黄土色になつた。A solution prepared by dissolving 89.39 ml of anhydrous sodium carbonate in 1500 ml of water and heating it to 40 DEG C. was added thereto over 20 seconds while supplying 5.5 m3/hour of air. A white precipitate was formed, which rapidly turned blue, dark blue, and bluish green, then turned to ocher color after 90 minutes. The temperature was raised to 50°C and the resulting sheet was sampled. The pH of the suspension was 33, and as a result of electron microscopic observation, needle-shaped crystals with a length of 0.5 microns and a width of 0.03 to 0.05 microns were observed, and X-ray diffraction confirmed that it had a goethite structure. did it. A solution of 275.39 sodium hydroxide dissolved in 4720 ml of water and heated to 50 DEG C. was added to this sheet suspension over 20 seconds, and air was introduced at a rate of 3 m/hour. After 1 hour, the viscosity began to increase and the color turned greenish ocher.

１２時間後反応を止め、プフナ一ろうとで済過した後ミ
キサーで水に再分散しろ過する操作を２回くり返した。After 12 hours, the reaction was stopped, and the procedure of redispersing in water using a mixer and filtering was repeated twice.

ろ過ケーキを１１０℃の乾燥器で乾燥し、石川式機械乳
鉢で粉砕した。得られたゲータイト粉末を電子顕微鏡で
観察した結果長さ０．５〜０．６ミクロン、巾０．０５
ミクロンの直方体状の結晶粒子が見られた。このゲータ
イト粉末を鉄板製ボートに入れ、外壁温を６００℃に保
つた鉄製１２ｃ７ｎφの管状炉で毎分１．５２のプロパ
ンガスを流しながら６０分間還元し、得られたマグネタ
イトを炉内温度を２５０℃に保つてある箱型炉で６０分
間空気酸化してガンマ酸化第二鉄を得た。このガンマ酸
化第二鉄を銅チユーブに詰め１０００エルステツドの直
流磁場ヒステリシスカーブトレーサーを用いて測定した
保磁力は充填密度０．７９／〜で３５９エルステツドだ
つた。実帷例 ２ 炭酸ナトリウム水溶液を２０秒かけて加えた後窒素ガス
を毎時３ｍ゜の割合で１０分間送入した後に空気送入を
始めた他は実帷例１と全く同条件で反応させて得たゲー
タイトは長さ０．６〜０．７ミクロン巾０．０７ミクロ
ンの直方体状結晶で、これから得たガンマ酸化鉄の保磁
力は０．７ｇ／Ｃｒｉｔで３４９エルステツドだつた。The filter cake was dried in a dryer at 110°C and ground in an Ishikawa mechanical mortar. Observation of the obtained goethite powder with an electron microscope revealed a length of 0.5 to 0.6 microns and a width of 0.05 microns.
Micron rectangular crystal particles were observed. This goethite powder was placed in a steel plate boat and reduced for 60 minutes while flowing propane gas at a rate of 1.52/min in a steel 12c7nφ tubular furnace whose outer wall temperature was maintained at 600°C. Gamma ferric oxide was obtained by air oxidation for 60 minutes in a box furnace maintained at .degree. This gamma ferric oxide was packed in a copper tube and the coercive force measured using a 1000 oersted DC magnetic field hysteresis curve tracer was 359 oersted at a packing density of 0.79/~. Practical Example 2 The reaction was carried out under exactly the same conditions as Practical Example 1, except that after adding the sodium carbonate aqueous solution over 20 seconds, nitrogen gas was introduced at a rate of 3 mm per hour for 10 minutes, and then air supply was started. The obtained goethite was a rectangular parallelepiped crystal with a length of 0.6 to 0.7 microns and a width of 0.07 microns, and the coercive force of the gamma iron oxide obtained therefrom was 349 oersted at 0.7 g/Crit.

実帷例 ３ 水酸化ナトリウム水溶液にヘキサメタ燐酸ナトリウム０
．７２５９を加えた他は実泡例１と全く同条件で反応さ
せて得たゲータイトは長さ０．６ミクロン巾０．０５ミ
クロンの短冊状結晶で、これから得たガンマ酸化鉄の保
磁力は０．７９／ｄで３７５エルステツドだつた。Practical example 3 Sodium hexametaphosphate in aqueous sodium hydroxide solution
．． Goethite obtained by reacting under exactly the same conditions as Example 1 except that 7259 was added was a rectangular crystal with a length of 0.6 microns and a width of 0.05 microns, and the coercive force of the gamma iron oxide obtained from this was 0. It was .79/d and 375 oersted.

実池例 ４〜６ 水酸化ナトリウム水溶液に、ヘキサメタ燐酸ナトリウム
を次の量加えた他は実兎例１と全く同条件で反応させ、
得られたゲータイト及びガンマ酸化第二鉄について測定
した結果は次の通りだつた。Practical Examples 4 to 6 The reaction was carried out under exactly the same conditions as in Practical Example 1, except that the following amount of sodium hexametaphosphate was added to the sodium hydroxide aqueous solution,
The obtained goethite and gamma ferric oxide were measured and the results were as follows.

実施例 ７〜９水酸化ナトリウム水溶液にメタ珪酸ナト
リウムを次の量加えた他は実施例１と全く同条件で反応
させ、得られたゲータイト及びガンマ酸化第二鉄につい
て測定した結果は次の通りだつた。Examples 7 to 9 The reaction was carried out under exactly the same conditions as in Example 1 except that the following amount of sodium metasilicate was added to the sodium hydroxide aqueous solution, and the results of measurement of the obtained goethite and gamma ferric oxide were as follows. It was.

実施例 １０ 水酸化ナトリウム水溶液にヘキサメタ燐酸ナトリウム０
．７５９、メタ珪酸ナトリウム０．８５９を加えた以外
は実施例１と全く同条件で反応させたところ得られたゲ
ータイトの長さ、巾は０．５ミクロン対０．０４ミクロ
ン、それから生成したガンマ酸化鉄の保磁力は３６８エ
ルステツドだつた。Example 10 Sodium hexametaphosphate 0 in sodium hydroxide aqueous solution
．． 759, the reaction was carried out under exactly the same conditions as in Example 1 except that 0.859 sodium metasilicate was added, and the length and width of the goethite obtained were 0.5 μm vs. 0.04 μm. The coercive force of iron was 368 oersted.

実施例 １１塩化第一鉄（ＦｅＣｌ２ｎＨ２Ｏ）３９８
９にゲータイト以外のオキシ水酸化鉄の生成を妨げるた
め硫酸第一鉄７水塩１８５９を混合し塩酸少量を加え、
水２８３０ｍ１に溶解した。Example 11 Ferrous chloride (FeCl2nH2O) 398
In order to prevent the formation of iron oxyhydroxide other than goethite, ferrous sulfate heptahydrate 1859 was mixed with 9, and a small amount of hydrochloric acid was added.
Dissolved in 2830 ml of water.

これを反応槽に入れ４０℃に保つた。無水炭酸ナトリウ
ム９２．３９を水１５００ｍ１に溶解し４０℃に保つた
。This was placed in a reaction tank and maintained at 40°C. 92.39 ml of anhydrous sodium carbonate was dissolved in 1500 ml of water and kept at 40°C.

第一鉄塩溶液に、吹込管から空気を毎時５．５ｍ３送入
しながら炭酸ナトリウム水溶液を２０秒かけて加えた。
白色の沈澱が生成し青色を経て６５分后に黄土色になつ
た。温度を５０℃に上げ、生成したシートをサンプリン
グした。懸濁液のＰＨは３．２を示し電子顕微鏡観察の
結果長さ０．４ミクロン、巾０．０２〜０．０２５ミク
ロンの針状結晶が見られ、Ｘ線回析ではゲータイト構造
の回析線のみを示した。次でシート懸濁液に水酸化ナト
リウム２８７９とヘキサメタ燐酸ナトリウム２．９９と
を水４７００７ｎ１に溶解し５０℃にした水溶液を２０
秒間かけて加えた。１２時間後縁をおびた黄土色の生成
物懸濁液を実施例１と同様に沢過、水洗、乾燥、粉砕し
て得た粉末はＸ線回析でゲータイト構造のみを示し、電
子顕微鏡観察で長さ０．７ミクロン、巾０．０４ミクロ
ンの短冊状結晶が見られた。The sodium carbonate aqueous solution was added to the ferrous salt solution over 20 seconds while blowing 5.5 m3 of air per hour through the blow tube.
A white precipitate was formed, which turned blue and turned ocher after 65 minutes. The temperature was raised to 50°C and the resulting sheet was sampled. The pH of the suspension was 3.2, and as a result of electron microscopic observation, needle-shaped crystals with a length of 0.4 microns and a width of 0.02 to 0.025 microns were observed, and X-ray diffraction revealed a goethite structure. Only the lines are shown. Next, an aqueous solution of 2879 sodium hydroxide and 2.99 sodium hexametaphosphate dissolved in 47007 n1 of water and heated to 50°C was added to the sheet suspension.
Added over a period of seconds. The powder obtained by filtering, washing with water, drying, and pulverizing the ocher-colored product suspension with a trailing edge for 12 hours in the same manner as in Example 1 showed only a goethite structure in X-ray diffraction, and was observed under an electron microscope. A rectangular crystal with a length of 0.7 microns and a width of 0.04 microns was observed.

このゲータイトを還元、酸化して得たガンマ酸化鉄の保
磁力は３７８エルステツドだつた。比較例 １ 比較例−１は従来のゲータイトの製法のうち、アルカリ
法の実験例である。The coercive force of gamma iron oxide obtained by reducing and oxidizing this goethite was 378 oersted. Comparative Example 1 Comparative Example 1 is an experimental example using an alkaline method among conventional goethite manufacturing methods.

硫酸第一鉄７水塩７８１９を水２６３０ｍ１に溶解して
５０℃に保ち、３ｍ３／時の空気を送入しながら、水酸
化ナトリウム３９０９を水６１９０ｍ１にとかして５０
℃にした水溶液を２０秒かけて加えた。Ferrous sulfate heptahydrate 7819 was dissolved in 2630 ml of water, kept at 50°C, and while introducing air at 3 m3/hour, sodium hydroxide 3909 was dissolved in 6190 ml of water to give 50 ml of ferrous sulfate heptahydrate.
The aqueous solution at 0.degree. C. was added over 20 seconds.

若干青みをおびた白色から青灰色を経て３０分後には黄
土色に変つた。２時間後から粘度が高くなりわずかに緑
色をおびて来た。The color changed from slightly bluish white to bluish-gray and then to ocher after 30 minutes. After 2 hours, the viscosity increased and the mixture became slightly green.

１６時間後反応を止め淵過、水洗、乾燥、粉砕して得た
ゲータイトは長さ０．５５ミクロン、巾０，０３ミクロ
ンの針状結晶からなり、実帷例１と同条件で生成させた
ガンマ酸化第二鉄の保磁力は０．７９／ＣＴｉｔで３７
７エルステツドだつた。After 16 hours, the reaction was stopped, and the goethite obtained by filtering, washing with water, drying, and pulverization consisted of needle-shaped crystals with a length of 0.55 microns and a width of 0.03 microns, and was produced under the same conditions as in Example 1. The coercive force of gamma ferric oxide is 0.79/CTit, which is 37.
It was 7 ersted.

比較例 ２ 水酸化ナトリウム水溶液にヘキサメタ燐酸ナトリウム２
．９９を加えた他は比較例１と全く同条件で反応させ、
得られたゲータイト及びガンマ酸化第二鉄について測定
した結果は次の通りだつた。Comparative Example 2 Sodium hexametaphosphate 2 in aqueous sodium hydroxide solution
．． The reaction was carried out under exactly the same conditions as in Comparative Example 1 except that 99 was added.
The obtained goethite and gamma ferric oxide were measured and the results were as follows.

ゲータイトの長さ０，４〜０．５ミクロン、巾０．０２
５〜０．０３ミクロン、ガンマ酸化第二鉄の保磁力は０
．７９／（−！ｒｌで３４１エルステツドだつた。比較
例 ３水酸化ナトリウム水溶液にメタ珪酸ナトリウムを
３．４９加えた他は比較例１と全く同条件で反応させた
ところ対角線が０．０２５ミクロンの６角板状〜立方状
のマグネタイトが生成した。Goethite length 0.4-0.5 microns, width 0.02
5 to 0.03 microns, the coercive force of gamma ferric oxide is 0
．． 79/(-!rl was 341 oersted. Comparative Example 3 The reaction was carried out under exactly the same conditions as in Comparative Example 1 except that 3.49% of sodium metasilicate was added to the aqueous sodium hydroxide solution, and the diagonal line was 0.025 μm. Hexagonal plate-shaped to cubic magnetite was produced.

比較例 ４ これは本発明のシート生成工程で第一鉄塩水溶液にアル
カリ金属の炭酸塩の水溶液を加えた後、空気送入をはじ
める前に３０分間熟成を行つた実験例である。Comparative Example 4 This is an experimental example in which an aqueous solution of an alkali metal carbonate was added to an aqueous ferrous salt solution in the sheet production process of the present invention, and then aged for 30 minutes before the introduction of air.

硫酸第一鉄７水塩、水、無水炭酸ナトリウム、水の量は
全て実抱例１と全く同条件とし反応槽に撹拌機をとりつ
け空気の送入を行うことなく４０℃の硫酸第一鉄水溶液
に４０℃の炭酸ナトリウム水溶液を２０秒かけて加えた
。この懸濁液を３０分間ゆつくり撹拌して熟成させた後
撹拌機をとり除き空気送入を行い、あとは実施例１と全
く同条件で反応を行つた。この実験で得られたシートは
０．２〜０．５ミクロンの範囲の長さにばらつき巾が大
きくずんぐりした結晶からなり最終生成物であるゲータ
イトは長さ１ミクロン、巾０．０３〜０．１ミクロンの
大きな結晶が多く、凝集がひどい。これから得られたガ
ンマ酸化第二鉄の保磁力は０．７９／ＣＴｌ．で３０７
エルステツドだつた。比較例 ５比較例−５は、「酸性
法」の実１験例である。The amounts of ferrous sulfate heptahydrate, water, anhydrous sodium carbonate, and water were all the same as in Example 1, and the reaction tank was equipped with a stirrer and ferrous sulfate was heated at 40°C without introducing air. A 40°C aqueous sodium carbonate solution was added to the aqueous solution over 20 seconds. After this suspension was slowly stirred for 30 minutes and aged, the stirrer was removed and air was introduced, and the reaction was then carried out under exactly the same conditions as in Example 1. The sheets obtained in this experiment were made up of chunky crystals with varying widths ranging from 0.2 to 0.5 microns, and the final product, goethite, was 1 micron long and 0.03 to 0.0 microns wide. There are many large crystals of 1 micron, and the aggregation is severe. The coercive force of gamma ferric oxide obtained from this is 0.79/CTl. So 307
It was Ersted. Comparative Example 5 Comparative Example 5 is an experimental example of the "acidic method".

シート生成反応は実症例−１と全く同様に反応させ、得
られたシート懸濁液の温度を６０℃まで昇温し空気５．
５ｍ３／時の中にアンモニアガスを混入した。アンモニ
アガスの混入量は残存第一鉄が６時間で消費される様に
制御し反応後期ではＦｅ＋１が消失するまでＰＨを４以
下に抑えるため混入量を徐々に下げた。約７時間でＦｅ
＋１が消費され反応を止めた。得られたゲータイトは長
さ０，５〜０．６ミクロン、巾０．０５〜０．０６ミク
ロンで、先端が鈍角三角形にとがつた板状結晶だつた。
これから得られたガンマ酸化第二鉄の保磁力は０．７９
／Ｃｒｉｔで３４９エルステツドだつた。比較例 ６ 比較例−６は、ガンマオキシ水酸化鉄やガンマオキシ水
酸化鉄の生成を妨げる硫酸第一鉄を併用しないで塩化第
一鉄を５３１９用いた以外は実帷例１と全く同条件で反
応させた。The sheet production reaction was carried out in exactly the same manner as in Actual Case-1, and the temperature of the obtained sheet suspension was raised to 60°C, and air was heated to 5.
Ammonia gas was mixed into 5 m3/hour. The amount of ammonia gas mixed in was controlled so that the remaining ferrous iron was consumed in 6 hours, and in the latter stage of the reaction, the amount of mixed ammonia gas was gradually lowered to keep the pH below 4 until Fe+1 disappeared. Fe in about 7 hours
+1 was consumed and the reaction stopped. The obtained goethite was a plate-shaped crystal with a length of 0.5 to 0.6 microns, a width of 0.05 to 0.06 microns, and an obtuse triangular tip.
The coercive force of gamma ferric oxide obtained from this is 0.79
/Crit was 349 oersted. Comparative Example 6 In Comparative Example 6, the reaction was carried out under exactly the same conditions as in Practical Example 1, except that 5319 ferrous chloride was used without concomitant use of ferrous sulfate, which inhibits the production of gamma oxyiron hydroxide or gamma oxyiron hydroxide. I let it happen.

シートのＸ線回析を行つた結果ゲータイトとベータオキ
シ水酸化鉄及び少量のガンマオキシ水酸の混合物である
ことを示していた。電子顕微鏡による観察では長さ１ミ
クロン、巾０．７５ミクロンの短冊状の結晶と長さ０．
４ミクロン、巾０．０２ミクロンの針状結晶とが見られ
た。又高アルカリ中で成長させて得た生成物はＸ線回析
の結果ゲータイト単相であることを示し、電子顕微鏡に
よる観察では長さ０．６ミクロン、巾０．１５ミクロン
の板状結晶と長さ０．６ミクロン、巾０．０５ミクロン
の短冊状結晶とが見られた。X-ray diffraction analysis of the sheet showed that it was a mixture of goethite, beta iron oxyhydroxide, and a small amount of gamma oxyhydroxide. Observation using an electron microscope reveals that the crystals are strip-shaped with a length of 1 micron and a width of 0.75 micron.
Needle-shaped crystals with a width of 4 microns and a width of 0.02 microns were observed. X-ray diffraction of the product grown in a highly alkaline environment showed that it was a single phase of goethite, and observation using an electron microscope showed that it was a plate-shaped crystal with a length of 0.6 microns and a width of 0.15 microns. Strip-shaped crystals with a length of 0.6 microns and a width of 0.05 microns were observed.

Claims (1)

【特許請求の範囲】[Claims] １ 硫酸第一鉄の水容液又は塩化第一鉄と硫酸第一鉄の
混合物の水容液を充分撹拌された状態に保ちながら、３
０分未満で鉄塩の５〜５０％の量を中和するのに必要な
量のアルカリ金属の炭酸塩の水容液又はアルカリ金属の
水酸化物の水容液を加えかつ３０〜６５℃に液温を調節
し、この温度に保ちながら直ちに空気を送入してゲータ
イト構造をもつ結晶核シートを生成させ、次にこのシー
トを含む懸濁液に、その中に残存する鉄塩の全てを中和
してＰＨが１．２以上になるのに必要な量の水酸化ナト
リウム又は水酸化カリウムの水容液を加え、次いで充分
撹拌された状態を保ちながら、４０〜７５℃の温度に保
ち、空気を送入して前記シート上にゲータイトを析出成
長させることを特徴とするゲータイトの製法。1 While keeping an aqueous solution of ferrous sulfate or a mixture of ferrous chloride and ferrous sulfate in a well-stirred state,
Add an amount of aqueous alkali metal carbonate or aqueous alkali metal hydroxide necessary to neutralize 5-50% of the iron salt in less than 0 minutes and at 30-65°C. Adjust the temperature of the liquid to 1, and while keeping it at this temperature, air is immediately introduced to generate a crystal nucleus sheet with a goethite structure, and then all of the iron salts remaining in the suspension containing this sheet are removed. Add the necessary amount of aqueous sodium hydroxide or potassium hydroxide to neutralize the water to a pH of 1.2 or higher, and then heat to a temperature of 40 to 75°C while maintaining sufficient stirring. 1. A method for producing goethite, which comprises maintaining the sheet and blowing air to cause goethite to precipitate and grow on the sheet.