JPH0859231A - Production of flaky rehydrating alumina - Google Patents
Production of flaky rehydrating aluminaInfo
- Publication number
- JPH0859231A JPH0859231A JP6201974A JP20197494A JPH0859231A JP H0859231 A JPH0859231 A JP H0859231A JP 6201974 A JP6201974 A JP 6201974A JP 20197494 A JP20197494 A JP 20197494A JP H0859231 A JPH0859231 A JP H0859231A
- Authority
- JP
- Japan
- Prior art keywords
- alumina
- particle size
- gibbsite
- size distribution
- diameter
- 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.)
- Granted
Links
Landscapes
- Compositions Of Oxide Ceramics (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Catalysts (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は活性アルミナ成形体原料
用或いは充填剤用等に適した再水和性アルミナ粉末の製
造方法に関する。更に詳細には、高細孔容積・高表面
積、高強度を有する活性アルミナ成形体或いは高アスペ
クト比を有し隠蔽力が大きく吸着性に優れた充填剤を提
供し得る再水和性アルミナ粉末の製造方法に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rehydratable alumina powder suitable for use as a raw material for an activated alumina compact or as a filler. More specifically, a rehydrated alumina powder capable of providing an activated alumina compact having a high pore volume, a high surface area, and a high strength, or a filler having a high aspect ratio and a large hiding power and an excellent adsorptivity. The present invention relates to a manufacturing method.
【０００２】[0002]
【従来の技術】活性アルミナ成形体は乾燥剤、吸着剤、
触媒、各種担体等に使用されている。これらの用途には
成形体内部への分子拡散速度を大きくする為、成形体の
細孔容積、特に細孔半径が１００オングストローク以上
のマクロ細孔容積を大きくすることが要求される。また
触媒成分、脱臭剤、香料、吸着剤等の各種薬液を活性ア
ルミナ成形体に担持する場合、担持量を大きくする目的
から高比表面積の成形体が要求される。また、触媒或い
は担体を振動がある箇所で使用する場合には機械的強度
（耐摩耗性）が要求され、これら全ての物性を満足する
活性アルミナ成形体は極めて少ない。更にコージェライ
ト等のセラミック成形体への被着用活性アルミナや樹
脂、塗料、紙等に対する吸着性充填剤としては、付着性
が高く、隠蔽力が大きい活性アルミナ粉末が求められて
いる。2. Description of the Related Art Activated alumina moldings are desiccants, adsorbents,
It is used as a catalyst and various carriers. In these applications, in order to increase the molecular diffusion rate inside the molded body, it is required to increase the pore volume of the molded body, particularly the macropore volume having a pore radius of 100 ang stroke or more. Further, when various chemicals such as catalyst components, deodorants, fragrances, adsorbents, etc. are carried on the activated alumina molded product, a molded product having a high specific surface area is required for the purpose of increasing the amount supported. In addition, when the catalyst or the carrier is used in a place subject to vibration, mechanical strength (wear resistance) is required, and there are very few activated alumina compacts satisfying all of these physical properties. Further, as an adsorbent filler for activated alumina to be adhered to a ceramic molded body such as cordierite, resin, paint, paper, etc., activated alumina powder having high adhesiveness and high hiding power is required.
【０００３】これらの要求を達成するための活性アルミ
ナ成形体の製造法としては、例えば （１）アルミニウム塩の中和によりゲルを析出し、これ
を洗浄・乾燥・成形・焼成する方法に於いて、析出条件
を制御する方法が知られている（特公平２−１７６７号
公報）。 （２）再水和し得るアルミナに繊維状燃焼性有機添加物
を混合し、成形し、再水和した後、４５０℃〜６５０℃
の温度条件下で焼成する方法が知られている（特開昭４
９−６００６号公報）。さらには、 （３）平均粒子径が約１〜３５μでその粒径分布の四分
偏差値が約１．５以下の再水和性アルミナを成形し、再
水和した後焼成することによりマクロ細孔容積が大で、
且つ耐磨耗強度が優れた低密度活性アルミナ成形体を製
造する方法（特公昭６３−２４９３２号公報）が知られ
ている。As a method for producing an activated alumina compact to achieve these requirements, for example, (1) a method of precipitating a gel by neutralizing an aluminum salt and washing, drying, shaping and firing the gel A method of controlling the deposition conditions is known (Japanese Patent Publication No. 2-1767). (2) 450 ° C. to 650 ° C. after mixing fibrous combustible organic additive with alumina that can be rehydrated, molding and rehydrating
There is known a method of firing under the temperature conditions of
9-6006). Further, (3) a rehydratable alumina having an average particle size of about 1 to 35 μm and a quartile deviation value of the particle size distribution of about 1.5 or less is molded, rehydrated and then fired to form a macro particle. Has a large pore volume,
Also known is a method (Japanese Patent Publication No. 63-24932) for producing a low-density activated alumina compact having excellent abrasion resistance.
【０００４】上記（１）のゲル析出時の条件を制御する
方法では、高細孔容積・高表面積の成形体を得られる
が、この方法によって得た成形体は単に物理的に結合し
ているのみなので、強度が低いという欠点がある。また
（２）の公知の燃焼性有機物を添加する方法は、これを
焼失せしめるに際し焼成コントロールが極めて困難であ
り、しかも、高温で長時間の焼成を必要とし、活性アル
ミナ成形体の比表面積の低下を招く等の不都合をも有す
る。更に（３）の四分偏差値が約１．５以下の再水和性
アルミナを成形し再水和し焼成する方法は、高細孔容積
・高表面積・高強度の活性アルミナ成形体を得ることが
できるが、四分偏差値が約１．５以下の再水和性アルミ
ナを得る為にアルミン酸ソーダを特定の条件で加水分解
する必要があったり、水酸化アルミニウムを分級したり
する必要があり、経済性に難点があった。また、水酸化
アルミニウムを粉砕し仮焼し四分偏差値が約１．５以下
の再水和性アルミナを得る方法についても、通常、商業
的観点より採用されるボールミルや振動ミル等の粉砕メ
ディアによって粉砕する場合には、極めて高頻度で分級
を行いながら粉砕する必要があり、製品回収率が著しく
低く、やはり経済性に問題があった。加えてこれら従来
法により得られる活性アルミナ粉末は塊状であり、樹
脂、塗料、紙等に対する吸着性充填剤としては付着性や
隠蔽力が大きい薄板状の活性アルミナ粉末が求められて
いた。By the method (1) for controlling the conditions during gel precipitation, a molded product having a high pore volume and a high surface area can be obtained, but the molded product obtained by this method is merely physically bonded. It has the disadvantage of low strength. In addition, the known method (2) of adding a combustible organic substance is extremely difficult to control firing when burning it off, and further requires firing at a high temperature for a long time, which lowers the specific surface area of the activated alumina molded body. There is also an inconvenience such as causing. Furthermore, the method of forming rehydrated alumina having a quartile deviation value of about 1.5 or less in (3), rehydrating and firing, obtains an activated alumina molded body having high pore volume, high surface area and high strength. However, it is necessary to hydrolyze sodium aluminate under specific conditions or classify aluminum hydroxide in order to obtain rehydrated alumina having a quartile deviation value of about 1.5 or less. There was a difficulty in economic efficiency. Regarding the method of pulverizing and calcination of aluminum hydroxide to obtain rehydratable alumina having a quartile deviation value of about 1.5 or less, a pulverizing medium such as a ball mill or a vibration mill, which is usually adopted from a commercial viewpoint, is also used. In the case of crushing by means of crushing, it is necessary to carry out crushing while performing classification at an extremely high frequency, the product recovery rate is extremely low, and there was also a problem in economic efficiency. In addition, the activated alumina powder obtained by these conventional methods is in a lump form, and as an adsorbent filler for resins, paints, papers, etc., a thin plate-shaped activated alumina powder having high adhesiveness and hiding power has been demanded.
【０００５】[0005]
【発明が解決しようとする課題】このような事情に鑑
み、本発明者等は、廉価に経済的方法で高細孔容積・高
表面積・高強度の活性アルミナ成形体を得ることがで
き、且つ、高アスペクト比を有し隠蔽力が大きく吸着性
に優れた充填剤を提供し得る再水和性アルミナ粉末を得
るべく鋭意研究を重ねた結果、本発明に到達したもので
ある。In view of such circumstances, the present inventors can obtain an activated alumina compact having a high pore volume, a high surface area and a high strength by an inexpensive and economical method, and The present invention has been achieved as a result of intensive research to obtain a rehydratable alumina powder capable of providing a filler having a high aspect ratio, a large hiding power, and an excellent adsorptivity.
【０００６】[0006]
【課題を解決するための手段】即ち本発明は、中心粒子
径が約１０μ以上で、一次粒子が約８μ以上のギブサイ
トを気流式粉砕機を用いて粉砕し、次いで、約５００〜
１２００℃の熱ガス中に分散させ０．１秒〜１０秒間接
触させて瞬間仮焼し、中心粒子径が約１μ〜２０μで粒
径分布の四分偏差値が約１．７以下で且つ径（ｄ）と厚
さ（ｔ）の比（ｄ／ｔ）が約５〜５０の薄片状再水和性
アルミナの製造方法を提供するにある。That is, according to the present invention, gibbsite having a central particle size of about 10 μm or more and primary particles of about 8 μm or more is crushed by using an air flow type crusher, and then about 500-about.
The particles are dispersed in hot gas at 1200 ° C., contacted for 0.1 second to 10 seconds and instantaneously calcined, and the central particle diameter is about 1 μm to 20 μm and the quartile deviation value of the particle size distribution is about 1.7 or less and the diameter. It is an object of the present invention to provide a method for producing flaky rehydrated alumina having a ratio (d / t) of (d) to thickness (t) of about 5 to 50.
【０００７】以下、本発明を詳細に説明する。本発明に
於いて、ギブサイトとは工業的にはバイヤー工程から得
られる三水酸化アルミニウムであり、その中心粒子径は
約１０μ以上である。原料とするギブサイトの中心粒子
径が１０μ以下の場合には粒子径（ｄ）と厚み（ｔ）の
比ｄ／ｔが５〜５０の薄片状の再水和性アルミナは得ら
れない。中心粒子径の上限は特にないが、バイヤー工程
で通常製造される約２００μまでのギブサイトであれば
使用可能である。ギブサイトの粒子径は一次粒子が凝集
もしくは塊状になった所謂二次粒子よりなり、通常、数
分の１μ〜約５０μの一次粒子径より構成されている
が、本発明に於いて使用するギブサイトは一次粒子径が
約８μ以上、好ましくは約１０μ〜４０μのものが使用
される。使用するギブサイトの一次粒子径が上記範囲に
満たない場合には、以降の粉砕条件や焼成条件を満足す
る場合であっても、粒径分布の四分偏差値が大きく、ま
た薄板状の再水和性アルミナを得ることはできない。Hereinafter, the present invention will be described in detail. In the present invention, gibbsite is industrially aluminum trihydroxide obtained from the Bayer process, and its central particle size is about 10 μm or more. When the central particle diameter of gibbsite as a raw material is 10 μm or less, flaky rehydratable alumina having a particle diameter (d) to thickness (t) ratio d / t of 5 to 50 cannot be obtained. There is no particular upper limit on the central particle size, but gibbsite up to about 200 μm, which is usually produced in the Bayer process, can be used. The particle size of gibbsite is composed of so-called secondary particles in which primary particles are agglomerated or agglomerated, and is usually composed of a few 1 μm to about 50 μm of the primary particle size, but the gibbsite used in the present invention is Those having a primary particle size of about 8 μm or more, preferably about 10 μm to 40 μm are used. If the primary particle size of the gibbsite used is less than the above range, the quartile deviation value of the particle size distribution is large, and the thin plate-like re-water is used even if the subsequent pulverization conditions and firing conditions are satisfied. It is not possible to obtain a compatible alumina.
【０００８】原料として使用されるギブサイトの純度
は、異物を含まないものであれば特に制限されないが通
常、Ｎａ2 Ｏ含有量は０．０２〜１重量％程度である。
また、粉砕に供するギブサイトが湿潤状態のときは、粉
砕機への投入が容易なように予め乾燥することが推奨さ
れる。The purity of gibbsite used as a raw material is not particularly limited as long as it does not contain foreign matters, but the content of Na 2 O is usually about 0.02 to 1% by weight.
When the gibbsite to be crushed is in a wet state, it is recommended to dry it beforehand so that it can be easily put into the crusher.
【０００９】本発明に於いて粉砕機は気流式粉砕機を用
いることを必須とする。気流式粉砕機はジェットミルと
も称され、粉砕機構は気流の運動エネルギーを利用し、
それに随伴されて被粉砕物が粒子同士或いは装置壁と衝
突することにより衝撃力が発生し、粉砕が行われる型式
のものであり、より具体的には、気流衝撃式粉砕機、気
流衝突板式粉砕機、対向気流式粉砕機等の各種のタイプ
があるが、基本的にはどのようなタイプのものであって
もよく、実作業上からは、簡単な分級機能が組み込まれ
ているタイプの方が粗粒の残量が少なくなるので好まし
い。特に粒子間衝突による粉砕が行われ、分級機能によ
り粗粒がリサイクルされるようなタイプの気流衝撃式粉
砕機が最も推奨される。In the present invention, it is essential to use an airflow type crusher as the crusher. The airflow type crusher is also called a jet mill, and the crushing mechanism uses the kinetic energy of the airflow,
It is a type in which crushing is carried out when the crushed objects collide with each other or particles collide with each other or the apparatus wall, and more specifically, the crushing is performed. There are various types of machines, such as a crusher and a counter-current air crusher, but basically any type can be used. Is preferable since the residual amount of coarse particles is reduced. In particular, an airflow impact type crusher of the type in which crushing is performed by collision between particles and coarse particles are recycled by the classification function is most recommended.
【００１０】粉砕の程度は粉砕機へのギブサイトの供給
速度及び気流の元圧によって調節する。気流の元圧を高
くすると粒子の衝突速度が大きくなり、粉砕粒径は小さ
くなる。供給速度を大きくすると衝突頻度は増えるが、
衝突時の速度が減少するので、通常の操作条件範囲では
粉砕粒径は大きくなる。粉砕品の中心粒子径は、活性ア
ルミナ成形体原料或いは充填剤として最適な約１μ〜２
０μ、好ましくは約３μ〜１５μになるように上記の操
作条件を調整する。代表的な操作条件としては、元圧６
ｋｇ／ｃｍ2 Ｇの場合、気流量１Ｎｍ3／ｈ当たり砕量
は０．２ｋｇ／ｈである。The degree of crushing is controlled by the feed rate of gibbsite to the crusher and the original pressure of the air stream. When the original pressure of the air flow is increased, the collision speed of particles is increased and the crushed particle size is decreased. Increasing the supply rate increases the frequency of collisions,
Since the velocity at the time of collision is reduced, the crushed particle size becomes large in the range of normal operating conditions. The center particle size of the crushed product is about 1 μ to 2 which is the most suitable as the raw material for the activated alumina compact or the filler.
The above operating conditions are adjusted to be 0 μ, preferably about 3 μ to 15 μ. A typical operating condition is a source pressure of 6
In the case of kg / cm 2 G, the crushing amount is 0.2 kg / h per 1 Nm 3 / h of air flow rate.
【００１１】気流の種類は粉砕機材質、水酸化アルミニ
ウム或いは再水和性アルミナに対して反応性、吸着性を
有しない物であれば特に限定はされないが、空気を用い
ることが最も経済的である。The type of air flow is not particularly limited as long as it is a material having no reactivity or adsorptivity with respect to the material of the crusher, aluminum hydroxide or rehydratable alumina, but it is most economical to use air. is there.
【００１２】粉砕処理の終わったギブサイトはサイクロ
ンやバグフィルター等によって捕集する。粉砕品の四分
偏差値を小さくする為、サイクロンを複数機設置すると
か、或いはサイクロンとバグフィルターを併設し、後半
の捕集機に飛散した微粒分を除いても良い。Gibbsite which has been crushed is collected by a cyclone, a bag filter or the like. In order to reduce the quartile deviation value of the crushed product, a plurality of cyclones may be installed, or a cyclone and a bag filter may be installed side by side to remove the fine particles scattered in the collector in the latter half.
【００１３】粉砕後のギブサイトは次に公知の条件で瞬
間仮焼し、再水和性アルミナにする。再水和性アルミナ
とは、水酸化アルミニウムを熱分解した遷移アルミナ
中、例えばχ，ρ−アルミナ及び無定形アルミナ等、１
００℃以下で再水和可能なアルミナである。瞬間仮焼
は、代表的には、焼成雰囲気温度約５００℃〜１２００
℃、線速度約５ｍ／秒〜約５０ｍ／秒の気流中に同伴さ
せて、接触時間約０．１秒〜約１０秒の条件で灼熱減量
３〜１０重量％まで焼成することにより実施される。気
流中で焼成された粉末は通常サイクロン、バグフィルタ
ー、電気集塵機等公知の方法で気流より分離、回収され
る。製品の四分偏差値を小さくする為、サイクロンを複
数置く、或いはサイクロンとバグフィルターを併設し、
後半の捕集機に飛散した微粒分を除いても良い。The gibbsite after grinding is then calcined under known conditions to give rehydrated alumina. Rehydratable alumina refers to transitional alumina obtained by thermally decomposing aluminum hydroxide, for example, χ, ρ-alumina and amorphous alumina.
It is an alumina that can be rehydrated below 00 ° C. Instant calcination is typically performed at a firing atmosphere temperature of about 500 ° C to 1200 ° C.
It is carried out by being entrained in an air flow having a linear velocity of about 5 m / sec to about 50 m / sec at a temperature of 0 ° C. and firing up to a burning loss of 3 to 10% by weight under the condition of a contact time of about 0.1 sec to about 10 sec. . The powder calcined in an air stream is usually separated and collected from the air stream by a known method such as a cyclone, a bag filter and an electrostatic precipitator. In order to reduce the quartile deviation value of the product, multiple cyclones are placed, or a cyclone and a bag filter are installed side by side.
Fine particles scattered in the latter half of the collector may be removed.
【００１４】このようにして得た再水和性アルミナは、
中心粒径が約１μ〜２０μ、特には約３μ〜１５μで粒
径分布の四分偏差値が約１．７以下、特には１．６以下
である。その他の物性については灼熱減量３〜１０重量
％、ＢＥＴ比表面積が１５０〜４００ｍ2 ／ｇ、結晶形
主成分はχ，ρ−アルミナ、窒素吸着法による細孔容積
は０．１〜０．３cm3 ／ｇである。The rehydratable alumina thus obtained is
The central particle diameter is about 1 to 20 µ, particularly about 3 to 15 µ, and the quartile deviation value of the particle diameter distribution is about 1.7 or less, particularly 1.6 or less. Regarding other physical properties, ignition loss is 3 to 10% by weight, BET specific surface area is 150 to 400 m 2 / g, crystalline form main component is χ, ρ-alumina, and pore volume by nitrogen adsorption method is 0.1 to 0.3 cm. 3 / g.
【００１５】上記した本発明方法により得た再水和性ア
ルミナは図１に示すように薄板状であり、径（ｄ）と厚
さ（ｔ）の比ｄ／ｔが約５〜約５０である。このような
形状になるのは、気流式粉砕機で粉砕時に一次粒径を限
定したギブサイト結晶のｃ軸と垂直な方向に結晶が劈開
する為と考えられる。また、このような割れ方をするこ
とより、極端な微粉の発生が少なく、粉砕品の四分偏差
値が低いものと考えられる。ギブサイト結晶が壊れた
後、例えばギブサイトを焼成することにより遷移アルミ
ナ、或いはαアルミナ等となした後、気流式粉砕を行っ
ても、薄板状の遷移アルミナやアルミナは得られない。
また、原料であるギブサイト結晶の一次粒子径が約８μ
以下の場合も、部分的には薄板状となるものの、不定形
の塊状粒子が混在した物となり隠蔽性、吸着性に優れた
再水和性アルミナは得られない。The rehydratable alumina obtained by the above-mentioned method of the present invention is in the form of a thin plate as shown in FIG. 1, and the ratio d / t of the diameter (d) to the thickness (t) is about 5 to about 50. is there. It is considered that such a shape is caused by the fact that the crystal is cleaved in the direction perpendicular to the c-axis of the gibbsite crystal having a limited primary particle size during pulverization with an air flow type pulverizer. Further, it is considered that such fine cracking causes less generation of extremely fine powder and lowers the quartile deviation value of the ground product. After the gibbsite crystals are broken, for example, even if the gibbsite is fired to obtain transition alumina, α-alumina, or the like, and then air flow type pulverization is performed, thin plate transition alumina or alumina cannot be obtained.
In addition, the primary particle size of the gibbsite crystal, which is the raw material, is about 8μ.
Also in the following cases, although it becomes a thin plate partly, it becomes a mixture of irregular-shaped lump particles, and rehydrated alumina excellent in hiding property and adsorptivity cannot be obtained.
【００１６】このようにして得られた再水和性アルミナ
は常法に従い活性アルミナ成形体やαアルミナ成型体或
いは充填剤等に適用可能である。例えば、活性アルミナ
の成形に於いては、（１）転動造粒機に再水和性アルミ
ナに水を共に供給し造粒する方法、（２）再水和性アル
ミナを金型で圧縮成形する方法、（３）水と混合後押出
機で成形する、等の方法が可能であり、形状も球状、円
柱状、リング状、板状、ハニカム状、塊状等に成形され
る。The rehydratable alumina thus obtained can be applied to an activated alumina molded body, an α-alumina molded body, a filler or the like according to a conventional method. For example, in the molding of activated alumina, (1) a method in which water is supplied to a rehydrating alumina together with a rolling granulator to granulate, and (2) compression molding of the rehydrating alumina with a mold. And (3) mixing with water and molding with an extruder, and the shape is also spherical, cylindrical, ring-shaped, plate-shaped, honeycomb-shaped, lump-shaped or the like.
【００１７】得られた成形体は、次いで成形体自体の機
械的強度を高める為に再水和に足る時間、室温〜１２０
℃、好ましくは５０〜９０℃の水中、水蒸気中又は水蒸
気含有ガス中で保持され再水和される。再水和は一般に
１分〜１週間行われる。再水和時間が長いほど、また温
度が高いほど機械的強度が大きくなるが、１２０℃以上
となると製品の表面積が低下し好ましくない。上記の温
度は水蒸気処理中の成形体の温度であり、再水和性アル
ミナは成形再水和時に発熱する為、室温で密閉容器中で
放熱を防止することによっても再水和は可能である。The obtained molded product is then rehydrated for a sufficient time to increase the mechanical strength of the molded product itself at room temperature to 120 ° C.
Rehydrated by holding in water, steam or a gas containing steam at 0 ° C, preferably 50-90 ° C. Rehydration is generally performed for 1 minute to 1 week. The longer the rehydration time and the higher the temperature, the greater the mechanical strength. However, when the rehydration time is 120 ° C. or higher, the surface area of the product decreases, which is not preferable. The above temperature is the temperature of the molded body during the steam treatment, and rehydration alumina generates heat during molding and rehydration, so rehydration is also possible by preventing heat dissipation in a closed container at room temperature. .
【００１８】再水和された成形体は続いて焼成し，成形
体中の付着水分及び結晶水を除く。焼成温度は通常３０
０〜１３００℃であり、焼成時間は約１０分〜約１００
時間である。焼成温度、時間は、成形体製品の目標結晶
形、細孔径、或いは表面積により簡単な予備実験により
選択すればよい。焼成は燃焼ガス、電気ヒーターによる
間接加熱、赤外線加熱等で実施される。焼成に先立って
自然乾燥，熱風乾燥、真空乾燥等の方法で付着水分を除
去して置くことも可能である．The rehydrated molded body is subsequently fired to remove the attached water and crystal water in the molded body. The firing temperature is usually 30
0 to 1300 ° C., firing time is about 10 minutes to about 100
Time. The firing temperature and time may be selected by a simple preliminary experiment depending on the target crystal form, pore size, or surface area of the molded product. Firing is performed by combustion gas, indirect heating with an electric heater, infrared heating, or the like. It is also possible to remove the adhering water by a method such as natural drying, hot air drying or vacuum drying prior to baking.
【００１９】このような本発明方法により得られた再水
和性アルミナを用いることにより、球状での成形体の場
合、通常、充填嵩密度が０．５０ｋｇ／ｌ〜０．７０ｋ
ｇ／ｌで、かつ細孔半径が２５０オングストローク以上
の細孔容積が約０．０５ｃｍ 3 ／ｇ以上で、耐摩耗強度
が約１．５％以下のものが得られる。Re-water obtained by such a method of the present invention
By using a compatible alumina
In general, the packed bulk density is 0.50 kg / l to 0.70 k
g / l and pore radius is 250 ang stroke or more
Pore volume is about 0.05 cm 3/ G or more, abrasion resistance strength
Of about 1.5% or less is obtained.
【００２０】活性アルミナ成形体の製造に際し、所望と
する細孔容積、強度を減じない範囲で他の無機化合物を
添加することができる。そのような無機化合物の例とし
ては、再水和性のないアルミナ例えばαアルミナ、アル
ミニウム塩、シリカ、粘土、タルク、ベントナイト、ゼ
オライト、コーディエライト、チタニア、アルカリ金属
塩、アルカリ土類金属塩、希土類金属塩、ジルコニア、
ムライト、シリカアルミナ等がある。酸化物以外の塩を
添加した場合は、成形体焼成温度は塩の分解温度以上に
することが必要である。再水和処理、乾燥或いは焼成後
の成形体を酸性成分含有する水溶液と接触させ、必要な
らば酸性分と接触後の成形体を焼成することも可能であ
る。この処理により活性アルミナ成形体中の不純物であ
るＮａ2 Ｏが除去でき、また表面を酸性にする効果があ
る。During the production of the activated alumina compact, other inorganic compounds can be added within the range that does not reduce the desired pore volume and strength. Examples of such inorganic compounds include non-rehydratable alumina such as α-alumina, aluminum salts, silica, clay, talc, bentonite, zeolite, cordierite, titania, alkali metal salts, alkaline earth metal salts, Rare earth metal salts, zirconia,
There are mullite, silica-alumina, etc. When a salt other than an oxide is added, it is necessary that the firing temperature of the molded body be equal to or higher than the decomposition temperature of the salt. It is also possible to bring the shaped body after rehydration treatment, drying or firing into contact with an aqueous solution containing an acidic component, and if necessary, to bake the shaped body after contact with the acidic component. By this treatment, Na 2 O which is an impurity in the activated alumina compact can be removed and the surface can be acidified.
【００２１】[0021]
【発明の効果】以上詳述した本発明方法によれば、廉価
に、活性アルミナ成形体原料或いは充填剤として最適な
粒径分布の四分偏差値が約１．７以下、普通には１．６
以下で結晶形状が薄板状の再水和性アルミナを得ること
を可能としたことより、活性アルミナ成形体となす場合
には、高比表面積、高細孔容積、高強度の成形体が得ら
れ、また充填剤の用途にあっては吸着性、隠蔽力に優れ
た活性アルミナ粉末を提供することが可能となるもの
で、その産業的効果は頗る大である。According to the method of the present invention described in detail above, the optimum quartile deviation value of the particle size distribution as a raw material for an activated alumina compact or a filler is about 1.7 or less, usually 1. 6
By making it possible to obtain rehydrated alumina having a thin crystal form below, a high specific surface area, high pore volume, and high strength molded body can be obtained when it is used as an activated alumina molded body. In addition, it is possible to provide an activated alumina powder having excellent adsorptivity and hiding power in the use of the filler, and its industrial effect is great.
【００２２】[0022]
【実施例】以下、本発明方法を実施例により更に詳細に
説明するが、本発明方法はかかる実施例により制限され
るものではない。尚、本文中に於いて示した物性値は次
の測定法によった。 ・マクロ細孔容積：水銀圧入法で求めた半径２５０オン
グストローク以上の細孔容積をいう。 ・摩耗率 ：ＪＩＳ Ｋ−１４６４に準じた。 ・粒径分布 ：日機装マイクロトラックＭＫ−２で
測定した。 ・四分偏差値 ：上記粒径分布の７５％（累積重量で
表す）径と２５％径の比の平方根をいう。 ・一次粒径 ：試料２ｇを一次粒子に解砕した後、
ブレーン比表面積を求めた。ブレーン比表面積より粒子
を球と仮定して一次粒子径を求めた。尚、一次粒子への
解砕圧力は予備試験により求め実施した。EXAMPLES The method of the present invention will now be described in more detail with reference to examples, but the method of the present invention is not limited to these examples. The physical properties shown in the text were measured by the following measuring methods. -Macropore volume: The volume of pores having a radius of 250 ang stroke or more, which is determined by the mercury porosimetry. -Abrasion rate: According to JIS K-1464. Particle size distribution: Measured with Nikkiso Microtrac MK-2. -Quaternary deviation value: The square root of the ratio of the 75% (expressed as cumulative weight) diameter to the 25% diameter in the above particle size distribution. -Primary particle size: After crushing 2 g of the sample into primary particles,
The Blaine specific surface area was determined. The primary particle size was calculated from the Blaine specific surface area assuming that the particles were spheres. The crushing pressure for the primary particles was determined by a preliminary test and carried out.
【００２３】実施例１ バイヤー工程で得られた中心粒径４２μで水分０．０３
％のギブサイトを原料とした。このギブサイトの一次粒
径は１１μであった。エア風量５．４Ｎｍ3 ／min で、
エア元圧力５．５Kg／cm2 Ｇに設定し、６０Kg／ｈでギ
ブサイトを気流衝撃式粉砕機に供給し、サイクロンによ
り回収した。回収率は９５％であった。得られた粉砕ギ
ブサイトの中心粒径は８．０μ、粒径分布の四分偏差値
が１．５０、重装密度１．０１ｇ／cm3 であった。粉砕
ギブサイトを約７００℃の熱ガス気流中に投入し瞬間仮
焼した。瞬間仮焼したものは灼熱原料が７％、結晶形が
χ，ρで表される再水和性アルミナであり、中心粒径が
８．０μ、粒径分布の四分偏差値が１．５２、重装密度
が０．６９ｇ／cm3 であった。実施例１で得た再水和性
アルミナのＳＥＭ写真を図１に示す。径と厚さの比が約
２０であった。Example 1 Median particle size obtained in the Bayer process was 42μ and water content was 0.03
% Gibbsite was used as a raw material. The primary particle size of this gibbsite was 11μ. With an air flow rate of 5.4 Nm 3 / min,
The air source pressure was set to 5.5 Kg / cm 2 G, and gibbsite was supplied to the airflow impact crusher at 60 Kg / h and collected by a cyclone. The recovery rate was 95%. The obtained pulverized gibbsite had a center particle size of 8.0 μ, a quartile deviation of the particle size distribution of 1.50, and a weight density of 1.01 g / cm 3 . The crushed gibbsite was put into a hot gas stream at about 700 ° C. and instantaneously calcined. The instantaneously calcined material is a rehydrating alumina whose burning form is 7% and whose crystal form is represented by χ and ρ, the central particle size is 8.0μ, and the quartile deviation of the particle size distribution is 1.52. The weight density was 0.69 g / cm 3 . An SEM photograph of the rehydratable alumina obtained in Example 1 is shown in FIG. The diameter to thickness ratio was about 20.
【００２４】実施例２ 実施例１と同じギブサイトを、エア流量約１４．５Ｎｍ
3 ／min でエア圧力５．５Kg／cm2 Ｇに設定した衝突板
付きの気流衝撃式粉砕機に２５０Kg／ｈで供給し粉砕
し、バグフィルターで回収した。粉砕品の中心粒径７．
４μ、粒径分布の四分偏差値１．５３であった。重装密
度０．９０ｇ／cm3 であった。粉砕ギブサイトを約７０
０℃の熱ガス気流中に投入し瞬間仮焼した。瞬間仮焼し
たものは灼熱原料が６％、結晶形がχ，ρで表される再
水和性アルミナであり、中心粒径が７．７μ、粒径分布
の四分偏差値が１．５３、重装密度が０．６９ｇ／c
m3 、径と厚さの比が約８であった。Example 2 The same gibbsite as in Example 1 was used, but the air flow rate was about 14.5 Nm.
It was supplied at 250 Kg / h to an air flow impact type crusher with an impact plate set at an air pressure of 5.5 Kg / cm 2 G at 3 / min, crushed, and collected by a bag filter. Central particle size of crushed product 7.
The value was 4μ and the quartile deviation value of the particle size distribution was 1.53. The weight density was 0.90 g / cm 3 . About 70 crushed gibbsite
It was put into a hot gas stream at 0 ° C. and instantaneously calcined. The instantaneous calcinated material is a rehydrating alumina whose burning form is 6% and whose crystal form is represented by χ and ρ, the central particle size is 7.7μ, and the quartile deviation of the particle size distribution is 1.53. , Heavy load density is 0.69g / c
m 3 , and the diameter-thickness ratio was about 8.
【００２５】比較例１ バイヤー工程で得られた中心粒径が１５μで水分が０．
０５％のギブサイトを原料とした。このギブサイトの一
次粒径は４μであった。エア風量５．４Ｎｍ3／min
で、エア元圧力５．７Kg／cm2 Ｇに設定し、６０Kg／ｈ
でギブサイトを気流衝撃式粉砕機に供給し、サイクロン
により回収した。得られた粉砕ギブサイトの中心粒径
４．９μ、粒径分布の四分偏差値１．４６、重装密度
０．９２ｇ／cm 3 であった。粉砕ギブサイトを約７００
℃の熱ガス気流中に投入し瞬間仮焼した。瞬間仮焼した
ものは灼熱原料が５％、結晶形がχ，ρで表される再水
和性アルミナであり、中心粒径が４．０μ、粒径分布の
四分偏差値が１．４２、重装密度が０．６９ｇ／cm3 、
径と厚さの比が約３であった。Comparative Example 1 The median particle size obtained in the Bayer process is 15 μm and the water content is 0.
05% gibbsite was used as the raw material. One of this Gibbsite
The secondary particle size was 4μ. Air volume 5.4Nm3/ Min
And the air source pressure is 5.7 kg / cm2Set to G, 60 kg / h
The gibbsite is supplied to the air impact type crusher with a cyclone.
Recovered by. Median particle size of the obtained ground gibbsite
4.9μ, quartile deviation of particle size distribution 1.46, heavy load density
0.92 g / cm 3Met. About 700 crushed gibbsite
It was put into a hot gas stream at a temperature of ℃ and calcined instantly. Burned for a moment
The thing is 5% of the burning raw material, and the re-water whose crystal form is represented by χ, ρ
It is a compatible alumina with a central particle size of 4.0μ and a particle size distribution of
Quadrature deviation value is 1.42, heavy load density is 0.69g / cm3,
The ratio of diameter to thickness was about 3.
【００２６】比較例２ 実施例１と同じギブサイト１０Kgを、内容積３０Ｌで鉄
球約８０Kgが入っている振動ミルにを入れ、振幅４mmで
１時間粉砕した。得られた粉砕ギブサイトの中心粒径は
１５．０μ、粒径分布の四分偏差値が１．８６、重装密
度１．５１ｇ／cm3 であった。粉砕ギブサイトを約７０
０℃の熱ガス気流中に投入し瞬間仮焼した。瞬間仮焼し
たものは灼熱原料が５．５％、結晶形がχ，ρで表され
る再水和性アルミナであり、中心粒径が１１．３μ、粒
径分布の四分偏差値が１．９５、重装密度が１．００ｇ
／cm3 であった。比較例２で得た再水和性アルミナのＳ
ＥＭ写真を図２に示す。径と厚さの比は約１であった。Comparative Example 2 10 kg of the same gibbsite as in Example 1 was placed in a vibrating mill having an internal volume of 30 L and about 80 kg of iron balls, and crushed for 1 hour at an amplitude of 4 mm. The obtained pulverized gibbsite had a central particle size of 15.0 μ, a quartile deviation value of the particle size distribution of 1.86, and a weight density of 1.51 g / cm 3 . About 70 crushed gibbsite
It was put into a hot gas stream at 0 ° C. and instantaneously calcined. The instantaneously calcined product is a rehydrating alumina whose burning material is 5.5% and whose crystal form is represented by χ and ρ, the central particle size is 11.3μ, and the quartile deviation value of the particle size distribution is 1. .95, heavy load density 1.00g
It was / cm 3 . S of the rehydratable alumina obtained in Comparative Example 2
The EM photograph is shown in FIG. The ratio of diameter to thickness was about 1.
【００２７】比較例３ 実施例１と同じギブサイト３００ｇを、内容積２Ｌでア
ルミナボール２．９Kgが入っている振動ミルにを入れ、
振幅４mmで１時間粉砕した。得られた粉砕ギブサイトの
中心粒径は８．０μ、粒径分布の四分偏差値が１．９３
であった。粉砕ギブサイトを約７００℃の熱ガス気流中
に投入し瞬間仮焼した。瞬間仮焼したものは灼熱原料が
５．５％、結晶形がχ，ρで表される再水和性アルミナ
であり、中心粒径が７．１μ、粒径分布の四分偏差値が
２．０３、重装密度が１．０２ｇ／cm3 、径と厚さの比
が約１であった。Comparative Example 3 300 g of the same gibbsite as in Example 1 was placed in a vibrating mill containing 2 L of internal volume and 2.9 kg of alumina balls.
It was crushed for 1 hour with an amplitude of 4 mm. The obtained pulverized gibbsite has a center particle size of 8.0 μ and a quartile deviation of the particle size distribution of 1.93.
Met. The crushed gibbsite was put into a hot gas stream at about 700 ° C. and instantaneously calcined. The instantaneously calcined material is a rehydrating alumina whose burning material is 5.5% and whose crystal form is represented by χ and ρ, the central particle size is 7.1μ, and the quartile deviation of the particle size distribution is 2 0.03, the loading density was 1.02 g / cm 3 , and the diameter-thickness ratio was about 1.
【００２８】比較例４ バイヤー工程から得られた中心粒径７．７μ、粒径分布
の四分偏差値が１．８５のギブサイトを市販分級機（風
篩式）を用いて分級した。分級後のギブサイトは中心粒
径６．８μで粒径分布の四分偏差値が１．３９であった
が、回収率は３０％と低かった。Comparative Example 4 Gibbsite having a center particle size of 7.7 μm and a quartile deviation of the particle size distribution of 1.85 obtained from the Bayer process was classified by using a commercial classifier (air sieve type). The gibbsite after classification had a central particle size of 6.8 μm and a quartile deviation of the particle size distribution of 1.39, but the recovery rate was low at 30%.
【００２９】実施例３及び４ 実施例１で得られた再水和性アルミナ１ｋｇに対し水約
０．６Kgを加え、皿型造粒機で直径２〜４mmの球状に成
形した後、該成形体を蓋付き容器に入れ密閉して８０℃
の温度で１６時間保持して再水和せしめた。次いでこの
成形体を電気炉に入れ１時間で３８０℃まで昇温し３時
間保持した。このようにして得られた活性アルミナ成形
体の物性は表１のとおりであった。上記と同様の方法で
実施例１で得られた再水和性アルミナを用い活性アルミ
ナ成形体を得た。この成形体の物性を表１に示す。Examples 3 and 4 About 0.6 kg of water was added to 1 kg of the rehydratable alumina obtained in Example 1, and the mixture was molded into a spherical shape having a diameter of 2 to 4 mm by a plate type granulator, and then the molding was performed. Put the body in a container with a lid and seal it at 80 ℃.
It was kept at this temperature for 16 hours for rehydration. Next, this molded body was placed in an electric furnace and heated to 380 ° C. for 1 hour and kept for 3 hours. The physical properties of the activated alumina compact thus obtained are as shown in Table 1. An activated alumina compact was obtained using the rehydratable alumina obtained in Example 1 in the same manner as above. Table 1 shows the physical properties of this molded product.
【００３０】比較例５ ・比較例２の成形 実施例３と同じ成形法で比較例２の再水和性アルミナを
成形し、活性アルミナ成形体を得た。この物性を表１に
示す。Comparative Example 5 Molding of Comparative Example 2 The rehydratable alumina of Comparative Example 2 was molded by the same molding method as in Example 3 to obtain an activated alumina molded body. The physical properties are shown in Table 1.
【００３１】[0031]
【表１】 [Table 1]
【図１】再水和性アルミナの粒子構造（形状）を示す顕
微鏡写真である。FIG. 1 is a micrograph showing the particle structure (shape) of rehydratable alumina.
【図２】再水和性アルミナの粒子構造（形状）を示す顕
微鏡写真である。FIG. 2 is a micrograph showing the particle structure (shape) of rehydratable alumina.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 // Ｃ０４Ｂ 35/10 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI technical display location // C04B 35/10
Claims (2)
８μ以上のギブサイトを気流式粉砕機により粉砕し、次
いで該粉砕物を５００℃〜１２００℃の熱ガス中、０．
１秒〜１０秒間接触させて瞬間仮焼する中心粒子径が１
μ〜２０μ、粒径分布の四分偏差値が１．７以下で且つ
径（ｄ）と厚さ（ｔ）の比（ｄ／ｔ）が５〜５０の薄片
状再水和性アルミナの製造方法。1. Gibbsite having a central particle size of 10 μm or more and a primary particle size of 8 μm or more is crushed by an air flow type crusher, and then the crushed product is heated in a hot gas at 500 ° C. to 1200 ° C.
The central particle diameter of 1 second to 10 seconds of contact and instantaneous calcination is 1
Production of flaky rehydrated alumina having a particle size distribution of μ to 20 μ, a quartile deviation of the particle size distribution of 1.7 or less, and a ratio (d / t) of the diameter (d) to the thickness (t) of 5 to 50. Method.
あることを特徴とする請求項１記載の薄片状再水和性ア
ルミナの製造方法。2. The method for producing flaky rehydrated alumina according to claim 1, wherein the quartile deviation value of the particle size distribution is about 1.6 or less.
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| JP20197494A JP3569969B2 (en) | 1994-08-26 | 1994-08-26 | Method for producing flaky rehydratable alumina |
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| JP20197494A JP3569969B2 (en) | 1994-08-26 | 1994-08-26 | Method for producing flaky rehydratable alumina |
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| JPH0859231A true JPH0859231A (en) | 1996-03-05 |
| JP3569969B2 JP3569969B2 (en) | 2004-09-29 |
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