JPH0446898B2 - - Google Patents
Info
- Publication number
- JPH0446898B2 JPH0446898B2 JP58198294A JP19829483A JPH0446898B2 JP H0446898 B2 JPH0446898 B2 JP H0446898B2 JP 58198294 A JP58198294 A JP 58198294A JP 19829483 A JP19829483 A JP 19829483A JP H0446898 B2 JPH0446898 B2 JP H0446898B2
- Authority
- JP
- Japan
- Prior art keywords
- ferrous
- iron
- salt
- aqueous
- aqueous solution
- 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 - Lifetime
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 24
- 238000007254 oxidation reaction Methods 0.000 claims description 19
- 239000007864 aqueous solution Substances 0.000 claims description 16
- 239000007789 gas Substances 0.000 claims description 15
- 229910001854 alkali hydroxide Inorganic materials 0.000 claims description 13
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 13
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 13
- 229960002089 ferrous chloride Drugs 0.000 claims description 12
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 12
- 230000001590 oxidative effect Effects 0.000 claims description 11
- 230000003647 oxidation Effects 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 6
- JZQOJFLIJNRDHK-CMDGGOBGSA-N alpha-irone Chemical compound CC1CC=C(C)C(\C=C\C(C)=O)C1(C)C JZQOJFLIJNRDHK-CMDGGOBGSA-N 0.000 claims description 5
- 239000012266 salt solution Substances 0.000 claims description 5
- 229910000859 α-Fe Inorganic materials 0.000 claims description 5
- 159000000007 calcium salts Chemical class 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 2
- CUPCBVUMRUSXIU-UHFFFAOYSA-N [Fe].OOO Chemical compound [Fe].OOO CUPCBVUMRUSXIU-UHFFFAOYSA-N 0.000 description 25
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 description 24
- 238000000034 method Methods 0.000 description 16
- 239000002245 particle Substances 0.000 description 16
- 239000011575 calcium Substances 0.000 description 14
- 150000003839 salts Chemical class 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 12
- 239000000243 solution Substances 0.000 description 11
- 239000013078 crystal Substances 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 230000005294 ferromagnetic effect Effects 0.000 description 6
- 229910002588 FeOOH Inorganic materials 0.000 description 5
- -1 chlorine ions Chemical class 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 150000002506 iron compounds Chemical class 0.000 description 5
- 238000006386 neutralization reaction Methods 0.000 description 5
- 229910006540 α-FeOOH Inorganic materials 0.000 description 5
- 238000002425 crystallisation Methods 0.000 description 4
- 230000008025 crystallization Effects 0.000 description 4
- 230000005291 magnetic effect Effects 0.000 description 4
- 239000003607 modifier Substances 0.000 description 4
- 239000000725 suspension Substances 0.000 description 4
- 230000002776 aggregation Effects 0.000 description 3
- 150000001450 anions Chemical class 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000000635 electron micrograph Methods 0.000 description 3
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical group N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 2
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 229910021577 Iron(II) chloride Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 235000011148 calcium chloride Nutrition 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910052500 inorganic mineral Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007721 medicinal effect Effects 0.000 description 1
- 239000011707 mineral Chemical class 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000007039 two-step reaction Methods 0.000 description 1
- 238000009279 wet oxidation reaction Methods 0.000 description 1
Landscapes
- Compounds Of Iron (AREA)
- Hard Magnetic Materials (AREA)
Description
本発明は、高分散性でしかも高表面積を有する
オキシ水酸化鉄の製造法に関する。更に詳しく
は、磁気記録用強磁性鉄酸化物（Fe3O4，γ−
Fe2O3金属鉄微粒子）の原料として好適な針状オ
キシ水酸化鉄の製造に関する。
近年、記録媒体に対する高性能化の必要性が強
く求められており、高密度記録、高出力特性及び
ノイズレベルの低下が要求されている。このよう
な要求を満足する磁性材料の特性は、粉体特性と
しては、微細で表面積が大きく且つ針状性が優れ
ていることであり、磁気特性においては飽和磁化
が大きく且つ所望する最適な保磁力を有すること
である。
強磁性鉄化合物の場合、針状性に優れているこ
とが必要である事から針状晶になり易いオキシ水
酸化鉄を出発原料とする方法が一般的である。従
つて、オキシ水酸化鉄を製造する方法が多数報告
されており、中でもアルカリ領域で第一鉄塩を湿
式酸化し、針状α−オキシ水酸化鉄を製造する方
法が実際に採用されている。
オキシ水酸化鉄に要求される粒子特性として、
枝分れがないこと、凝集体がないこと、粒度分布
の狭いこと、適切な大きさ及び針状比が大きいこ
となど多くの項目があり、これらはオキシ水酸化
鉄晶出工程が重要とされ、このため種々の元素を
添加して媒晶効果を期待したり、晶出条件を特定
したりするなど数多くの工夫がなされている。
例えば、媒晶剤として特開昭56−165302号で
は、アルカリ土類金属をPH11以上である水酸化第
一鉄のアルカリ性懸濁液中に存在させることが記
載されているが、硫酸第一鉄を用いる例のみが示
されている。
又、特開昭56−104718号では、オキシ水酸化鉄
の表層部へ周期律表第族に属する元素の化合物
を被着させることが記載されているが、被着時期
は特定しておらず、被着させることで後の工程、
具体的には還元または酸化工程での粒子の、破
損、破壊、焼結を防ぐことを目的としている。
反応条件としては特開昭56−22638号に40℃以
下でα−オキシ水酸化鉄を生成させ、40〜60℃に
昇温して結晶成長させる２段階反応が記載されて
いるが、この方法によれば完全に１本１本が分散
したオキシ水酸化鉄が得られない。
その他数多くの報告がなされているが、いずれ
もオキシ水酸化鉄の分散性が不十分であり、その
後の表面処理、焼成、酸化、還元工程へ悪影響を
及ぼし、強磁性鉄化合物の特性が十分満足できる
ものとはなつていない。現在求められている高性
能磁性材料では更に要求が厳しくなつており、粒
子の完全な分散化特に出発原料であるオキシ水酸
化鉄の分散化が必須条件となる。
本発明者らは、高表面積を有する強磁性鉄化合
物の製造法について鋭意研究を重ね、特に、反応
方法、条件について詳細な検討を行い、晶析技術
を深めていく中で、反応条件を厳しく制限し、又
媒晶剤として陽イオンと陰イオンの組合せを新た
に見い出したことで、非常に分散性の良いオキシ
水酸化鉄を製造することができるという知見を得
て本発明を完成するに至つた。
即ち、本発明は第一鉄塩水溶液の酸化反応によ
り、α−オキシ水酸化鉄を製造する方法におい
て、
第一鉄塩水溶液として、塩化第一鉄、水酸化ア
ルカリ及びカルシウム塩からなる水溶液を調製
し、該調製にあたつては、25℃以下の液温で塩化
第一鉄水溶液を、３〜８当量の水酸化アルカリ水
溶液に、鉄濃度が0.03〜0.3モル／リツトルとな
るように添加すると共に、第一鉄塩水溶液中に、
カルシウム塩を鉄に対して0.5〜２モル％存在す
るように添加し、
続いて、酸化率が50％以下となるように酸化性
ガスを供給した後、
不活性ガス雰囲気下で温度を上昇させて、40〜
80℃の温度とし、
再び酸化性ガスを供給し、酸化反応を完了させ
る
ことを特徴とする針状α−オキシ水酸化鉄の製造
法を提供するものである。
このような方法によれば、針状粒子の場合生じ
やすい長軸に平行な方向への凝集もなく、１本１
本に粒子が分散したオキシ水酸化鉄が得られ、後
の表面処理も均一に行うことができ、高表面積の
強磁性鉄化合物が得られる。
更に本発明について詳細に説明する。
本発明において使用する第一鉄塩は、塩化第一
鉄であり、通常よく多用される硫酸塩あるいは炭
酸塩、硝酸塩など他の鉱酸塩は使用できない。本
発明は晶析時のアニオンの媒晶効果を期待するも
のであり、塩素イオンとCaとの組合せが必須条
件であり、他のアニオンでは十分な媒晶効果が得
られない。従つて、添加する媒晶剤もCa塩に限
定される。Ca塩としては、塩酸塩、硝酸塩、炭
酸煙、硫酸塩など種々の塩を用いることができ
る。第一鉄塩に比しCa塩の量が少ないので種々
の塩を用いることができるが、好ましくは塩酸
塩、硝酸塩を用いる。Ca塩の添加は、鉄に対し
0.5〜２モル％の量、酸化性ガスの供給開始前ま
でに行う。具体的には、塩化第一鉄水溶液にCa
塩を添加する方法、水酸化アルカリ水溶液にCa
塩を添加する方法、塩化第一鉄水溶液及び水酸化
アルカリ水溶液のそれぞれにCa塩を添加する方
法、及び塩化第一鉄水溶液と水酸化アルカリ水溶
液との混合後にCa塩を添加する方法を例示する
ことができるが、好ましくは、塩化第一鉄水溶液
に添加する。Ca塩の添加を第一鉄塩水溶液のア
ルカリ剤による中和反応完了後の酸化性ガスによ
る酸化反応途中、もしくはこれ以降の工程で行つ
ても、本発明の意図する高表面積、強磁性鉄化合
物は得られない。
添加量は、0.5モル％未満ではCa塩の媒晶効果
が十分でなく、オキシ水酸化鉄が数本集合した凝
集体が存在するようになる。又、２モル％を越え
る量では、マグネタイトが析出し易くなり好まし
くない。
本発明において使用するアルカリとしては、
KOHやNaOH等の水酸化アルカリを用いる。
Na2CO3等の炭酸アルカリ、NH3の水溶液、尿素
などは、塩素イオンの媒晶効果を打ち消すので、
使用できない。
水酸化アルカリの量は、第一鉄塩に対し３〜８
当量用いる。使用量が３当量に満たない場合は、
マグネタイトが生成し易くなるし、オキシ水酸化
鉄の針状性が悪くなるので好ましくない。使用量
が８当量を越す場合は、オキシ水酸化鉄の凝集体
が存在するようになり好ましくない。
第一鉄塩水溶液の水酸化アルカリによる中和反
応は、Ca塩添加した塩化第一鉄水溶液を25℃以
下に保つた水酸化アルカリ水溶液に撹拌しながら
添加することで行う。
添加時の温度が25℃を越える場合、あるいは水
酸化アルカリ水溶液を塩化第一鉄水溶液に添加し
た場合、中和反応により生成する水酸化第一鉄の
結晶が大きくなつたり、凝集を生じたりするので
好ましくない。
更に中和反応後の反応液中のFe濃度が0.03〜
0.3モル／となるように塩化第一鉄水溶液及び
水酸化アルカリ水溶液の濃度を調整する。
Fe濃度が0.03モル／未満であると、マグネタ
イトが生成し易くなるので好ましくない。又、
0.3モル／を越える場合は、液中のスラリー濃
度高くなり粘度が上昇し、反応を均一に行うこと
が難しくなつたり、オキシ水酸化鉄の凝集体が存
在するようになり好ましくない。
更に、反応系内及び原料水溶液を不活性ガスで
置換することは、中和反応時の第一鉄イオンの酸
化を防ぐという点で望ましい方法である。
本発明において使用する酸化性ガスとは、酸素
を含むガスであり、空気あるいは酸素富化ガス、
あるいは酸素と不活性ガスとを混合して得たガス
などを用いる。
本発明では、酸化性ガスを用いて酸化反応によ
りオキシ水酸化鉄を製造する際、明確に二つの段
階に分けて酸化反応を行う。まず、一段目では25
℃以下の温度で酸化率10〜50％の範囲まで酸化す
る。
一段目の反応温度から25℃を越えると、オキシ
水酸化鉄の結晶成長速度が早くなり、析出オキシ
水酸化鉄が不揃いに成長する結果、粒度分布がひ
ろくなるし、オキシ水酸化鉄の凝集体が存在する
ようになり好ましくない。反応温度の下限は、酸
化性ガスの供給速度と関係するので、反応槽ガス
吹込み方法に適した温度を設定しなければならな
いが、一般的には５℃が下限となる。
酸化率が10％未満であると、二段目での酸化で
新たな核発生が生じ、粒度分布が広くなり好まし
くない。一方、50％を越える場合はオキシ水酸化
鉄が微細すぎるし、又、針状比も悪くなり好まし
くない。
一段目の酸化反応後、酸化性ガスを不活性ガス
に切替え、温度を40〜80℃へ上昇させる。設定温
度に達してから、再び酸化性ガスを供給し、酸化
反応を完結させる。
二段目の反応温度を40〜80℃としたのは、一段
目で発生させたオキシ水酸化鉄を成長させ、針状
性と粒子長さを所望する値にするためである。
このようにして得られるオキシ水酸化鉄は、凝
集のない分散した粒子であり、これを常法により
処理し、酸化、還元を行つて得られる鉄粉、γ−
Fe2O3等は、高表面積を有す磁気記録材料とな
る。
本発明に於て用いる媒晶剤カルシウム陽イオン
と塩素陰イオンの組合せは、先に詳述した特定条
件下のみで、その効果を如何なく発揮する。すな
わち、本発明の条件を満す反応条件下に於ては、
極めて分散性に優れたオキシ水酸化鉄が得られる
ものである。
以下、本発明を実施例により更に具体的に説明
する。
実施例 １
20℃に保つた1.6mol／のNaOH水溶液0.8
に、撹拌しながら、0.002mol／のCaCl2を含む
0.2mol／のFeCl2水溶液0.8を添加してFe
（OH）2とCa（OH）2の共沈物を含む懸濁液を得た。
この懸濁液を20℃に保ち、撹拌しながら、液中
に0.3／分の割合で空気を10分間吹き込み、
Fe2+イオンの一部をFe3+へ酸化した。この時の
酸化率〔Fe3+／（Fe2+＋Fe3+）×100〕は９％で
あつた。その後、空気を窒素ガスに切替え系内を
不活性ガス雰囲気とし、懸濁液の温度を50℃とし
た。次に、窒素ガスを空気に切替え0.1／分の
割合で吹き込み、反応を完了させ、α−FeOOH
を得た。
得られたα−FeOOHは、透過型電子顕微鏡観
察で、結晶形状、凝集状態、長さ、軸比などを測
定した。
形状は第１図に示すように棒状であり、平均長
さ約0.3μ、軸比（長軸／短軸）約15のよく分散し
た粒子となつていた。乾燥α−FeOOHのBET表
面積は、95m2／ｇであつた。
比較例 １
実施例１の方法において、FeCl2の代わりに、
FeSO4・7H2Oを使用し、第１表に記載した条件
でα−FeOOHを製造した。
結果は、第２表に示すが、第２図に示すような
凝集粒子となつた。
比較例 ２
実施例１の方法において、CaCl2の代わりに、
MgCl2を使用し、第１表に記載した条件でα−
FeOOHを製造した。
結果は第２表に示すが、第３図に示すような枝
分れの多い粒子となつた。
比較例 ３
実施例１の方法において、NaOH濃度を
4.8mol／とし、第１表に記載した条件でα−
FeOOHを製造した。
結果は第２表に示すが、第４図に示すような凝
集粒子が存在した。
実施例２〜９および比較例４，５
反応条件を第１表に記載するように種々変化さ
せて、α−FeOOHを製造した。得られたα−
FeOOHの粒子粉末特性を第２表に示す。
The present invention relates to a method for producing iron oxyhydroxide that is highly dispersible and has a high surface area. More specifically, ferromagnetic iron oxide for magnetic recording (Fe 3 O 4 , γ-
This invention relates to the production of acicular iron oxyhydroxide suitable as a raw material for Fe 2 O 3 (metallic iron fine particles). In recent years, there has been a strong need for improved performance in recording media, and high-density recording, high output characteristics, and lower noise levels are required. The characteristics of a magnetic material that satisfies these requirements include fine particles, a large surface area, and excellent acicularity, and magnetic properties such as large saturation magnetization and the desired optimal retention. It has magnetic force. In the case of a ferromagnetic iron compound, since it is necessary to have excellent needle-like properties, it is common to use iron oxyhydroxide, which tends to form needle-like crystals, as a starting material. Therefore, many methods for producing iron oxyhydroxide have been reported, and among them, a method in which acicular α-iron oxyhydroxide is produced by wet oxidation of ferrous salt in an alkaline region has been actually adopted. . The particle characteristics required for iron oxyhydroxide are as follows:
There are many requirements such as no branching, no agglomerates, narrow particle size distribution, appropriate size and high acicular ratio, and the iron oxyhydroxide crystallization process is important for these requirements. For this reason, many efforts have been made, such as adding various elements to expect a moderation effect and specifying crystallization conditions. For example, as a modifier, JP-A-56-165302 describes the presence of an alkaline earth metal in an alkaline suspension of ferrous hydroxide with a pH of 11 or higher; Only examples using . Furthermore, JP-A-56-104718 describes that a compound of an element belonging to group 3 of the periodic table is deposited on the surface layer of iron oxyhydroxide, but the time of deposition is not specified. , later process by depositing,
Specifically, the purpose is to prevent damage, destruction, and sintering of particles during the reduction or oxidation process. Regarding the reaction conditions, JP-A No. 56-22638 describes a two-step reaction in which α-iron oxyhydroxide is produced at 40°C or lower, and then the temperature is raised to 40 to 60°C to grow crystals. According to the method, it is not possible to obtain iron oxyhydroxide in which the iron oxyhydroxide is completely dispersed one by one. Many other reports have been made, but in all cases, the dispersibility of iron oxyhydroxide is insufficient, which adversely affects the subsequent surface treatment, firing, oxidation, and reduction processes, and the properties of the ferromagnetic iron compound are not fully satisfied. It hasn't become what it can be. The requirements for high-performance magnetic materials currently in demand are becoming even more stringent, and complete dispersion of particles, especially dispersion of iron oxyhydroxide as a starting material, is an essential condition. The inventors of the present invention have conducted extensive research into the production method of ferromagnetic iron compounds with a high surface area, and in particular, conducted detailed studies on reaction methods and conditions, and as they deepened their crystallization technology, In addition, by discovering a new combination of cations and anions as crystal modifiers, we were able to complete the present invention with the knowledge that it is possible to produce iron oxyhydroxide with very good dispersibility. I've reached it. That is, the present invention provides a method for producing α-iron oxyhydroxide by an oxidation reaction of an aqueous ferrous salt solution, which includes preparing an aqueous solution consisting of ferrous chloride, an alkali hydroxide, and a calcium salt as an aqueous ferrous salt solution. However, for this preparation, an aqueous ferrous chloride solution is added to an aqueous alkali hydroxide solution of 3 to 8 equivalents at a liquid temperature of 25°C or less so that the iron concentration is 0.03 to 0.3 mol/liter. In addition, in a ferrous salt aqueous solution,
Calcium salt is added in an amount of 0.5 to 2 mol% based on iron, and then an oxidizing gas is supplied so that the oxidation rate is 50% or less, and then the temperature is raised under an inert gas atmosphere. 40~
The present invention provides a method for producing acicular α-iron oxyhydroxide, which is characterized in that the temperature is set at 80°C, and an oxidizing gas is supplied again to complete the oxidation reaction. According to this method, there is no aggregation in the direction parallel to the long axis, which tends to occur with needle-shaped particles, and each particle is
Iron oxyhydroxide with dispersed particles can be obtained, the subsequent surface treatment can be performed uniformly, and a ferromagnetic iron compound with a high surface area can be obtained. Further, the present invention will be explained in detail. The ferrous salt used in the present invention is ferrous chloride, and other mineral salts such as sulfates, carbonates, and nitrates, which are commonly used, cannot be used. The present invention relies on the effect of the anion during crystallization, and the combination of chlorine ions and Ca is an essential condition; other anions cannot provide a sufficient effect as the medium. Therefore, the crystal modifier to be added is also limited to Ca salt. Various salts such as hydrochloride, nitrate, carbonate, and sulfate can be used as the Ca salt. Since the amount of Ca salt is smaller than ferrous salt, various salts can be used, but hydrochloride and nitrate are preferably used. Addition of Ca salt is effective against iron.
It is carried out in an amount of 0.5 to 2 mol % before the start of supplying the oxidizing gas. Specifically, Ca was added to the ferrous chloride aqueous solution.
How to add salt, Ca to aqueous alkali hydroxide solution
A method of adding salt, a method of adding Ca salt to each of an aqueous ferrous chloride solution and an aqueous alkali hydroxide solution, and a method of adding a Ca salt after mixing an aqueous ferrous chloride solution and an aqueous alkali hydroxide solution are exemplified. However, it is preferably added to an aqueous ferrous chloride solution. Even if Ca salt is added during the oxidation reaction with an oxidizing gas after the neutralization reaction of the ferrous salt aqueous solution with an alkaline agent is completed, or in the subsequent step, the high surface area, ferromagnetic iron compound intended by the present invention can be obtained. cannot be obtained. If the amount added is less than 0.5 mol %, the modulation effect of the Ca salt will not be sufficient, and aggregates of several iron oxyhydroxides will be present. Moreover, if the amount exceeds 2 mol %, magnetite tends to precipitate, which is not preferable. The alkali used in the present invention is
Use an alkali hydroxide such as KOH or NaOH.
Alkali carbonates such as Na 2 CO 3 , aqueous solutions of NH 3 , urea, etc. cancel the medicinal effect of chlorine ions, so
I can not use it. The amount of alkali hydroxide is 3 to 8 for ferrous salt.
Use equivalent amount. If the amount used is less than 3 equivalents,
This is not preferable because magnetite tends to be generated and the acicularity of iron oxyhydroxide deteriorates. If the amount used exceeds 8 equivalents, aggregates of iron oxyhydroxide will be present, which is not preferable. The neutralization reaction of an aqueous ferrous salt solution with an alkali hydroxide is carried out by adding an aqueous ferrous chloride solution to which a Ca salt has been added to an aqueous alkali hydroxide solution maintained at 25° C. or below while stirring. If the temperature at the time of addition exceeds 25°C, or if an alkali hydroxide aqueous solution is added to a ferrous chloride aqueous solution, the ferrous hydroxide crystals generated by the neutralization reaction may become larger or agglomerate. So I don't like it. Furthermore, the Fe concentration in the reaction solution after neutralization reaction is 0.03 ~
Adjust the concentrations of the ferrous chloride aqueous solution and the alkali hydroxide aqueous solution so that the concentration is 0.3 mol/. If the Fe concentration is less than 0.03 mol/mol, magnetite is likely to be generated, which is not preferable. or,
If it exceeds 0.3 mol/ml, the concentration of the slurry in the liquid increases and the viscosity increases, making it difficult to carry out the reaction uniformly or causing the presence of iron oxyhydroxide aggregates, which is not preferable. Furthermore, replacing the inside of the reaction system and the raw material aqueous solution with an inert gas is a desirable method in terms of preventing oxidation of ferrous ions during the neutralization reaction. The oxidizing gas used in the present invention is a gas containing oxygen, such as air or oxygen-enriched gas,
Alternatively, a gas obtained by mixing oxygen and an inert gas is used. In the present invention, when iron oxyhydroxide is produced by an oxidation reaction using an oxidizing gas, the oxidation reaction is clearly divided into two stages. First, in the first stage, 25
Oxidizes to an oxidation rate of 10-50% at temperatures below ℃. When the temperature exceeds 25°C from the first stage reaction temperature, the crystal growth rate of iron oxyhydroxide increases, and the precipitated iron oxyhydroxide grows irregularly, resulting in a wide particle size distribution and aggregates of iron oxyhydroxide. This is not desirable as it becomes present. Since the lower limit of the reaction temperature is related to the supply rate of the oxidizing gas, it is necessary to set a temperature suitable for the reaction tank gas injection method, but generally the lower limit is 5°C. If the oxidation rate is less than 10%, new nuclei will be generated in the second stage of oxidation, resulting in a wide particle size distribution, which is undesirable. On the other hand, if it exceeds 50%, the iron oxyhydroxide is too fine and the acicular ratio is also poor, which is not preferable. After the first stage oxidation reaction, the oxidizing gas is switched to an inert gas and the temperature is raised to 40-80°C. After reaching the set temperature, oxidizing gas is supplied again to complete the oxidation reaction. The reason why the reaction temperature in the second stage was set at 40 to 80°C was to allow the iron oxyhydroxide generated in the first stage to grow and to achieve the desired acicularity and particle length. The iron oxyhydroxide obtained in this way is a dispersed particle without agglomeration, and the iron powder obtained by treating this in a conventional manner and performing oxidation and reduction, γ-
Fe 2 O 3 and the like serve as magnetic recording materials with a high surface area. The combination of calcium cations and chloride anions used as crystal modifiers in the present invention exhibits its effects only under the specific conditions detailed above. That is, under reaction conditions that satisfy the conditions of the present invention,
Iron oxyhydroxide with extremely excellent dispersibility can be obtained. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 1.6mol/0.8 of NaOH aqueous solution kept at 20℃
containing 0.002 mol/CaCl 2 while stirring.
Fe by adding 0.8 mol/FeCl 2 aqueous solution
A suspension containing a coprecipitate of (OH) 2 and Ca(OH) 2 was obtained. This suspension was kept at 20°C, and while stirring, air was blown into the liquid at a rate of 0.3/min for 10 minutes.
Some of the Fe 2+ ions were oxidized to Fe 3+ . The oxidation rate [Fe 3+ /(Fe 2+ +Fe 3+ )×100] at this time was 9%. Thereafter, the air was replaced with nitrogen gas to create an inert gas atmosphere inside the system, and the temperature of the suspension was set at 50°C. Next, nitrogen gas was switched to air and blown at a rate of 0.1/min to complete the reaction, and α-FeOOH
I got it. The crystal shape, agglomeration state, length, axial ratio, etc. of the obtained α-FeOOH were measured using a transmission electron microscope. As shown in FIG. 1, the particles were rod-like, well-dispersed, and had an average length of about 0.3 μm and an axial ratio (major axis/minor axis) of about 15. The BET surface area of dry α-FeOOH was 95 m 2 /g. Comparative Example 1 In the method of Example 1, instead of FeCl2 ,
α-FeOOH was produced using FeSO 4 .7H 2 O under the conditions listed in Table 1. The results are shown in Table 2, and aggregated particles as shown in FIG. 2 were obtained. Comparative Example 2 In the method of Example 1, instead of CaCl2 ,
α- using MgCl 2 under the conditions listed in Table 1.
FeOOH was produced. The results are shown in Table 2, and the particles were highly branched as shown in Figure 3. Comparative Example 3 In the method of Example 1, the NaOH concentration was
4.8mol/α- under the conditions listed in Table 1
FeOOH was produced. The results are shown in Table 2, and aggregated particles as shown in FIG. 4 were present. Examples 2 to 9 and Comparative Examples 4 and 5 α-FeOOH was produced by varying the reaction conditions as shown in Table 1. The obtained α−
The particle powder properties of FeOOH are shown in Table 2.
【表】【table】
【表】【table】
【表】【table】
第１図は本発明の一実施例で得られたα−
FeOOHの結晶を表わす電子顕微鏡写真であり、
第２図、第３図、第４図は比較例にて得られたα
−FeOOHの結晶を表わす電子顕微鏡写真であ
る。なお、電子顕微鏡写真の倍率はいずれも
30000倍である。
Figure 1 shows α-
This is an electron micrograph showing crystals of FeOOH.
Figures 2, 3, and 4 show α obtained in the comparative example.
-An electron micrograph showing crystals of FeOOH. In addition, the magnification of all electron micrographs is
It is 30,000 times.
Claims (1)
シ水酸化鉄を製造する方法において、 第一鉄塩水溶液として、塩化第一鉄、水酸化ア
ルカリ及びカルシウム塩からなる水溶液を調製
し、該調製にあたつては、25℃以下の液温で塩化
第一鉄水溶液を、３〜８当量の水酸化アルカリ水
溶液に、鉄濃度が0.03〜0.3モル／リツトルとな
るように添加すると共に、第一鉄塩水溶液中に、
カルシウム塩を鉄に対して0.5〜２モル％存在す
るように添加し、 続いて、酸化率が50％以下となるように酸化性
ガスを供給した後、 不活性ガス雰囲気下で温度を上昇させて、40〜
80℃の温度とし、 再び酸化性ガスを供給し、酸化反応を完了させ
る ことを特徴とする針状α−オキシ水酸化鉄の製造
法。[Claims] 1. A method for producing α-ferrous oxyhydroxide by an oxidation reaction of an aqueous ferrous salt solution, wherein the aqueous ferrous salt solution is an aqueous solution consisting of ferrous chloride, an alkali hydroxide, and a calcium salt. For the preparation, add ferrous chloride aqueous solution to 3 to 8 equivalents of alkali hydroxide aqueous solution at a liquid temperature of 25°C or less so that the iron concentration is 0.03 to 0.3 mol/liter. At the same time, in the ferrous salt aqueous solution,
Calcium salt is added in an amount of 0.5 to 2 mol% based on iron, and then an oxidizing gas is supplied so that the oxidation rate is 50% or less, and then the temperature is raised under an inert gas atmosphere. 40～
A method for producing acicular α-iron oxyhydroxide, characterized in that the temperature is set at 80°C, and an oxidizing gas is supplied again to complete the oxidation reaction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58198294A JPS6090830A (en) | 1983-10-25 | 1983-10-25 | Manufacture of needlelike iron oxyhydroxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58198294A JPS6090830A (en) | 1983-10-25 | 1983-10-25 | Manufacture of needlelike iron oxyhydroxide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6090830A JPS6090830A (en) | 1985-05-22 |
| JPH0446898B2 true JPH0446898B2 (en) | 1992-07-31 |
Family
ID=16388733
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58198294A Granted JPS6090830A (en) | 1983-10-25 | 1983-10-25 | Manufacture of needlelike iron oxyhydroxide |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6090830A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63134523A (en) * | 1986-11-22 | 1988-06-07 | Chisso Corp | Production of needle-like iron alpha-oxyhydroxide particulate powder |
| EP1857414A1 (en) * | 2005-02-16 | 2007-11-21 | Japan Science and Technology Agency | Method for producing iron oxyhydroxide and adsorbing material comprising iron oxyhydroxide |
-
1983
- 1983-10-25 JP JP58198294A patent/JPS6090830A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6090830A (en) | 1985-05-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5645652A (en) | Spindle-shaped magnetic iron-based alloy particles containing cobalt and iron as the main ingredients and process for producing the same | |
| US5466306A (en) | Spindle-shaped magnetic iron based alloy particles | |
| JPS62167221A (en) | Production of lepidocrocite | |
| JPS5853688B2 (en) | Method for producing acicular alloy magnetic particle powder mainly composed of Fe-Mg | |
| JPH0368923B2 (en) | ||
| JPH0446898B2 (en) | ||
| JPH10226520A (en) | Hydrate iron oxide and production of ferromagnetic iron oxide | |
| JPH0633116A (en) | Ferromagnetic metallic powder for magnetic recording medium and production thereof | |
| JPS6135135B2 (en) | ||
| US5989516A (en) | Spindle-shaped geothite particles | |
| JPH0466817B2 (en) | ||
| JPH0130884B2 (en) | ||
| JPS62158801A (en) | Magnetic metallic particle powder essentially consisting of iron having spindle shape and production thereof | |
| JPH0446899B2 (en) | ||
| JP2965606B2 (en) | Method for producing metal magnetic powder | |
| JPS6149252B2 (en) | ||
| JP3737309B2 (en) | Multi-layered iron compound particles | |
| JPS6251898B2 (en) | ||
| JPS6313943B2 (en) | ||
| JPS59128293A (en) | Manufacture of needlelike crystal of alpha-iron oxyhydroxide | |
| JPS6021818A (en) | Preparation of acicular crystal of alphaoxy iron hydroxide | |
| JPS59128295A (en) | Manufacture of needlelike crystal of alpha-iron oxyhydroxide | |
| JPS6011300A (en) | Manufacture of needlelike alpha-iron oxyhydroxide crystal | |
| KR910009210B1 (en) | Method for manufacturing lepidocrocite | |
| JP3055308B2 (en) | Method for producing acicular magnetic iron oxide particles |