JP2015105222A - Porous granulated calcination product and production method thereof - Google Patents
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- 239000011148 porous material Substances 0.000 claims abstract description 58
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- HDYRYUINDGQKMC-UHFFFAOYSA-M acetyloxyaluminum;dihydrate Chemical compound O.O.CC(=O)O[Al] HDYRYUINDGQKMC-UHFFFAOYSA-M 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Glanulating (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
本発明は、多孔質造粒焼成体及びその製造方法に関する。 The present invention relates to a porous granulated fired body and a method for producing the same.
ここで、「焼成」とは、無数のアルミナ粒子からなる造粒体を、気孔内にアルミナ析出結晶が得られる温度（例えば、700℃）以上で高温処理して固結することをいう。ただし、気孔が完全に塞がれる完全焼結は含まない。 Here, “sintering” refers to solidifying a granulated body made of countless alumina particles at a temperature higher than the temperature (for example, 700 ° C.) at which alumina precipitate crystals are obtained in the pores. However, complete sintering in which the pores are completely blocked is not included.
なお、以下の説明で、配合単位を示す「％」、「部」は、特に断らない限り、それぞれ「質量％」および「質量部」を意味する。 In the following description, “%” and “part” indicating a blending unit mean “% by mass” and “part by mass”, respectively, unless otherwise specified.
また、各特性値は、下記の如く定義されるものである。 Each characteristic value is defined as follows.
「平均粒径」・・・メジアン径を意味し、レーザ回折法で測定した値（平均粒径５０μm未満）又はJIS標準網ふるいによる値（平均粒径50μｍ以上）。 “Average particle diameter” means a median diameter and is a value measured by a laser diffraction method (average particle diameter of less than 50 μm) or a value obtained by JIS standard mesh screen (average particle diameter of 50 μm or more).
「比表面積」・・・JIS Z 8830「ガス吸着による粉体の比表面積測定方法」（ＢＥＴ法）に準拠して測定した値。 “Specific surface area”: A value measured according to JIS Z 8830 “Method for measuring specific surface area of powder by gas adsorption” (BET method).
「真球度」・・・走査式電子顕微鏡（ＳＥＭ）による画像解析法による二値化測定法で測定した算術平均値（ｎ＝10）。 “Sphericality”: An arithmetic average value (n = 10) measured by a binarization measurement method by an image analysis method using a scanning electron microscope (SEM).
「気孔径」・・・走査式電子顕微鏡（ＳＥＭ）を用いた画像解析法の内の二値価測定法により求めた算術平均値（ｎ＝10）。 “Pore diameter”: an arithmetic average value (n = 10) obtained by a binary value measurement method among image analysis methods using a scanning electron microscope (SEM).
「圧縮強度」・・・JISR1608「ファインセラミックスの圧縮強さ試験方法」に準拠して測定した値。 “Compressive strength”: Value measured in accordance with JISR1608 “Testing method for compressive strength of fine ceramics”.
「析出結晶の大きさ」・・・走査式電子顕微鏡（ＳＥＭ）により計測した析出結晶の長径と短径の算術平均値（二軸平均径）（ｎ＝10）。 “Size of precipitated crystal” —Arithmetic average (biaxial average diameter) of major and minor diameters of a precipitated crystal measured by a scanning electron microscope (SEM) (n = 10).
「ソーダ成分」・・・JISR2216「耐火物製品の蛍光X線分析方法」に準拠して計測した値。 “Soda component”: Value measured in accordance with JISR2216 “XRF analysis method for refractory products”.
アルミナは、その高耐熱性及び低反応性に基づき、多岐にわたり利用されている。特にαアルミナの多孔質体は、機能性製品の材料として様々な用途、触媒担体、微生物固定床、培養床、ろ過媒体に使用されている。 Alumina is widely used based on its high heat resistance and low reactivity. In particular, a porous body of α-alumina is used as a material for functional products in various applications, catalyst carriers, microorganism fixed beds, culture beds, and filtration media.
そして、これらのアルミナの多孔質体には、簡便かつ安価に、細孔分布を制御でき高強度の触媒担体として使用可能であり、さらには、低ソーダ含有であることが要求されている（特許文献１）。 These alumina porous bodies are required to be able to control the pore distribution easily and inexpensively and be used as a high-strength catalyst carrier, and further to contain low soda (patents). Reference 1).
これらの要求に応えるために、特許文献１において、下記構成のαアルミナ成形体（造粒体）の製造方法が提案されている（請求項１、要約書等）。 In order to meet these requirements, Patent Document 1 proposes a method of manufacturing an α-alumina molded body (granulated body) having the following configuration (claim 1, abstract, etc.).
「粒径と重装嵩密度を制御したギブサイト結晶水酸化アルミニウムを仮焼することにより得られる少なくとも部分的に再水和性を有するアルミナ粉を水と混合し、この混合物を成形して成形体を得、この成形体を110〜200℃の湿潤雰囲気中または水蒸気中に保持して再水和させ、次いで再水和させた成形体を1200℃以上で焼成するα−アルミナ成形体の製造方法。」 “At least partially rehydratable alumina powder obtained by calcining gibbsite crystal aluminum hydroxide with controlled particle size and bulk density is mixed with water, and this mixture is molded to form a molded body The molded body is rehydrated while being held in a humid atmosphere or steam at 110 to 200 ° C., and then the rehydrated molded body is fired at 1200 ° C. or higher. . "
そして、特許文献１段落0051・0052には、仮焼した再水和性アルミナの粉末原料を、皿形造粒機を用いて、水をスプレーしながら直径２〜４ｍｍの球状の造粒体とし、該造粒体を焼成することが記載されている。 In Patent Document 1, paragraphs 0051 and 0052, the calcined rehydratable alumina powder raw material is formed into a spherical granule having a diameter of 2 to 4 mm while spraying water using a dish-type granulator. And firing the granulated body.
また、αアルミナの多孔質焼成体に関するものではないが、特許文献２では、下記構成の遷移アルミナ成形体（活性アルミナ成形体）（多孔質焼成体の前駆体）の製造方法が提案されている（請求項１、要約書等）。 Further, although not related to a porous sintered body of α-alumina, Patent Document 2 proposes a method for producing a transition alumina molded body (activated alumina molded body) (precursor of a porous sintered body) having the following configuration. (Claim 1, abstract, etc.).
「少なくとも部分的に再水和性を有する遷移アルミナ粉末を湿式成形し、再水和し、次いで再水和後の成形体を焼成して遷移アルミナ成形体の製造方法において、遷移アルミナ粉末の湿式成形時に中心粒径が0.01〜100μmのポリメタクリル酸エステルを主成分とする粉末もしくはラテックスを存在せしめることを特徴とする遷移アルミナ成形体の製造方法。」 “Transition alumina powder having at least partially rehydratability is wet-molded, rehydrated, and then the rehydrated molded body is fired to produce a transition alumina molded body. A process for producing a transition alumina molded body characterized in that a powder or latex mainly comprising a polymethacrylic acid ester having a central particle diameter of 0.01 to 100 μm is present during molding. ”
そして、特許文献２段落0032には、仮焼した再水和性アルミナに対して気孔形成剤であるポリメタクリル酸メチルを添加した混合粉末を、皿形造粒機を用いて、水をスプレーしながら直径２〜４ｍｍの球状の造粒体（湿式成形）とし、該造粒体を再水和処理後、焼成することが記載されている。 In paragraph 0032 of Patent Document 2, mixed powder obtained by adding polymethyl methacrylate, which is a pore-forming agent, to calcined rehydratable alumina is sprayed with water using a dish granulator. However, it is described that a spherical granulated body (wet molding) having a diameter of 2 to 4 mm is formed, and the granulated body is fired after rehydration treatment.
しかし、上記多孔質造粒焼成体又はその前駆体の製造方法は、いずれも、転動造粒した造粒体をオートクレーブ等に投入して再水和させる必要があり、生産工数および熱エネルギーコストが嵩んだ。また、これらの多孔質焼成体は、制御された同一径の気孔を有する場合においてさらなる大きな比表面積が、同一比表面積においてさらなる高強度を有することが要望されている。 However, any of the above methods for producing a porous granulated fired body or a precursor thereof requires that the tumbled granulated body be put into an autoclave or the like to be rehydrated, resulting in production man-hours and thermal energy costs. Was bulky. In addition, these porous fired bodies are required to have a larger specific surface area and a higher strength at the same specific surface area when they have controlled pores of the same diameter.
本発明の目的は、上記課題（問題点及び要望）を解決することができるアルミナの多孔質造粒焼成体及びその製造方法を提供することにある。 The objective of this invention is providing the porous granulation baking body of alumina which can solve the said subject (problem and request), and its manufacturing method.
本発明者らは、上記課題を解決するために、鋭意開発に努力をした結果、下記構成の多孔質造粒焼成体 (1)およびその製造方法(2)に想到した。 As a result of diligent development in order to solve the above problems, the present inventors have conceived a porous granulated fired body (1) having the following constitution and a production method (2) thereof.
(1)本発明に係る多孔質造粒焼成体は、無数のアルミナ粒子同士が、主として連通する気孔を造粒体粒子の断面全体に網目状に残存させて固結してなる多孔質造粒焼成体であって、前記気孔は、その内径が気孔形成剤の液滴径で制御されているとともに、その内面に無数のアルミナ析出結晶を有していることを特徴とする。 (1) The porous granulated calcined product according to the present invention is a porous granulated product in which countless alumina particles are consolidated by leaving the pores communicating mainly in the entire cross-section of the granulated particles. In the fired body, the pore has an inner diameter controlled by a droplet diameter of the pore-forming agent and has an infinite number of alumina precipitated crystals on the inner surface.
主として連通する気孔が造粒体粒子の断面全体に網目状に形成されているため、比表面積の大きなものが得やすいとともに、網目状の気孔径が均質であるため、造粒焼成体の強度および品質が安定し易い。また、気孔の内面に無数のアルミナ析出結晶を有するため、さらに比表面積が増大する。さらには、気孔の内面に形成された対向する析出結晶相互が融着結合することにより疑似的な補強柱が形成されて相対的に強度が増大する。 Since the pores that mainly communicate are formed in a mesh shape in the entire cross section of the granulated particles, it is easy to obtain a large specific surface area, and since the mesh pore size is uniform, the strength of the granulated fired body and Quality is easy to stabilize. In addition, since there are innumerable alumina precipitated crystals on the inner surfaces of the pores, the specific surface area is further increased. Furthermore, when the opposing precipitated crystals formed on the inner surface of the pores are fused and bonded, a pseudo reinforcing column is formed, and the strength is relatively increased.
(2)本発明に係る多孔性造粒焼成体の製造方法は、アルミナ微粉体からなる原料を、回転皿を備えた転動造粒機を用いて液剤噴霧しながら湿式造粒する造粒工程と、該造粒体を焼成する焼成工程とを含み、
前記造粒工程は、
1)回転皿の斜め下方部に位置する排出部に対向する上方部側から投入され、回転皿の外周部に沿って一次転動循環をする原料に対して、結晶析出剤を一次噴霧する工程、
2)前記一次転動循環の内側を二次転動循環する一次噴霧後原料に対して気孔形成剤を二次噴霧する工程、
3)前記二次転動循環の内側を三次転動循環する二次噴霧後原料に対して、結合剤を三次噴霧する工程、及び、
4)三次噴霧後原料を、さらなる転動循環により造粒成長を進行させて所要径の造粒体に整粒する工程、
の各副工程を含み、
前記一次・二次・三次噴霧を、それぞれ、一次・二次・三次転動循環する反転側部位で行う、ことを特徴とする。
(2) The method for producing a porous granulated fired body according to the present invention comprises a granulation step of wet granulating a raw material made of fine alumina powder while spraying a liquid agent using a rolling granulator equipped with a rotating dish. And a firing step of firing the granulated body,
The granulation step includes
1) A step of primary spraying of a crystal precipitation agent on a raw material which is introduced from an upper part side facing a discharge part located at an obliquely lower part of a rotating dish and performs primary rolling circulation along an outer peripheral part of the rotating dish. ,
2) a step of secondary spraying the pore-forming agent on the raw material after the primary spraying that undergoes secondary rolling circulation inside the primary rolling circulation;
3) The step of tertiary spraying the binder to the secondary sprayed raw material that undergoes tertiary rolling circulation inside the secondary rolling circulation; and
4) A step of granulating the raw material after the third spraying by further rolling circulation to make a granulated body of a required diameter,
Each sub-process of
The primary / secondary / tertiary spraying is performed on the reversing side portions where the primary, secondary, and tertiary rolling circulate, respectively.
上記製造方法においては、従来の如く、湿式造粒後の造粒体をオートクレーブ等に投入して再水和する必要がなく、生産工数および熱エネルギーコストが削減できる。また、各噴霧液を回転皿の別位置で噴霧することにより、それらの薬剤の単位時間噴霧量を調節でき、均質な比表面積、気孔径及び粒径を有する多孔質造粒焼成体を容易に得ることができる。 In the above production method, it is not necessary to put the granulated material after wet granulation into an autoclave or the like for rehydration as in the prior art, and the production man-hours and heat energy cost can be reduced. In addition, by spraying each spray liquid at a different position on the rotating dish, the amount of spraying of these drugs per unit time can be adjusted, and a porous granulated fired body having a uniform specific surface area, pore diameter and particle size can be easily obtained. Can be obtained.
なお、各噴霧位置が転動循環の反転側部位でないと、一次・二次の各転動循環の重なりが大きく、別位置での噴霧が困難となる。 In addition, if each spray position is not the inversion side site | part of rolling circulation, the overlap of each primary and secondary rolling circulation will be large, and spraying at another position will become difficult.
以下、本発明の多孔質造粒焼成体およびその製造方法について、図面を参照にしながら説明する。 Hereinafter, the porous granulated fired body of the present invention and the production method thereof will be described with reference to the drawings.
多孔質造粒焼成体の粒子１１は、無数のアルミナ粒子同士が、主として連通する気孔（以下単に「気孔」という。）１３を残存させて固結してなるものである（図１参照）。そして、気孔１３は、その内径が気孔形成剤の液滴径で制御されているとともに、その内面に無数のアルミナ析出結晶１５を有している。 The particles 11 of the porous granulated fired body are formed by innumerable alumina particles solidified with pores (hereinafter simply referred to as “pores”) 13 that mainly communicate with each other (see FIG. 1). The pore 13 has an inner diameter controlled by the droplet diameter of the pore-forming agent, and has countless alumina precipitated crystals 15 on the inner surface.
ここで、本造粒焼成体の実用的な特性を下記する。それらの範囲から適宜選定する。 Here, practical characteristics of the granulated fired body will be described below. Select from these ranges as appropriate.
１）平均粒径（メジアン径）：0.1〜５mm（望ましくは0.5〜５mm）、
２）比表面積（ＢＥＴ）：0.１〜20m２/ｇ（望ましくは0.5〜15m２/ｇ）、
３）真球度：1.0〜1.5、
４）気孔径：0.5〜50μm、
５）アルミナ析出結晶の大きさ（二軸平均径）：0.1〜５μm。
1) Average particle diameter (median diameter): 0.1 to 5 mm (preferably 0.5 to 5 mm),
2) Specific surface area (BET): 0.1 to 20 m 2 / g (preferably 0.5 to 15 m 2 / g),
3) Sphericality: 1.0-1.5,
4) Pore diameter: 0.5-50 μm,
5) Alumina precipitated crystal size (biaxial average diameter): 0.1 to 5 μm.
なお、気孔径が大きすぎると、造粒焼成粒子に必要な強度を得難くなる。 If the pore diameter is too large, it will be difficult to obtain the strength required for the granulated fired particles.
次に、本発明の多孔質造粒焼成体の製造方法について、図２〜５に基づいて説明する。 Next, the manufacturing method of the porous granulated fired body of the present invention will be described based on FIGS.
アルミナ微粉体を原料とし、回転皿を備えた転動造粒機を用いて薬剤被覆しながら造粒する造粒工程と、該造粒体を焼成する焼成工程とを含むことを前提とする。 It is premised on including a granulation step of granulating while using an alumina fine powder as a raw material while coating a drug using a rolling granulator equipped with a rotating dish, and a firing step of firing the granulated body.
原料として使用するアルミナ微粉体の特性は、製品である造粒焼成体における要求特性により異なる。例えば、触媒担体等に使用する場合は、多孔質造粒焼成体にソーダ含有率が低く且つ気孔分布が密である特性が要求される。このため、相対的に安価である仮焼アルミナ微粉体のうち、低ソーダアルミナ微粉体（αアルミナ）として上市されているものを好適に使用できる。具体的には、ソーダ（Ｎａ２Ｏ基準）含有率において、0.3％以下、さらには0.１％以下、粒径（メジアン）において、0.1〜100μm、さらには１〜５μmのものを使用することが望ましい。なお、原料であるアルミナ微粉体は、βアルミナやγアルミナ（ρ、χ、η、δを含む。）であってもよい。 The characteristics of the fine alumina powder used as a raw material vary depending on the required characteristics of the granulated fired product. For example, when used as a catalyst carrier or the like, the porous granulated fired body is required to have a characteristic that the soda content is low and the pore distribution is dense. For this reason, among the relatively inexpensive calcined alumina fine powders, those marketed as low soda alumina fine powders (α alumina) can be suitably used. Specifically, use a soda (Na 2 O standard) content of 0.3% or less, further 0.1% or less, and a particle size (median) of 0.1 to 100 μm, more preferably 1 to 5 μm. Is desirable. The alumina fine powder as a raw material may be β alumina or γ alumina (including ρ, χ, η, and δ).
薬剤としては、１）結晶析出剤（一次噴霧液）、２）気孔形成剤（二次噴霧液）、３）結合剤（三次噴霧液)を用いる。具体的には、下記の通りである。 As the drug, 1) a crystal precipitation agent (primary spray solution), 2) a pore-forming agent (secondary spray solution), and 3) a binder (tertiary spray solution) are used. Specifically, it is as follows.
１）結晶析出剤（一次噴霧液）：
結晶析出剤の分散質であるアルミニウム化合物としては、有機系、無機系を問わない。有機系としては、乳酸アルミニウム、アルミニウムアルコキシド、メチルアルミニウム（Ａｌ２（ＣＨ３）６）、エチルアルミニウム（Ａｌ２（Ｃ２Ｈ５）６）、酢酸アルミニウム等を、無機系としては、硝酸アルミニウム、塩化アルミニウム等を好適に使用できる。
1) Crystal precipitation agent (primary spray):
The aluminum compound that is the dispersoid of the crystal precipitating agent may be organic or inorganic. Examples of the organic system include aluminum lactate, aluminum alkoxide, methylaluminum (Al 2 (CH 3 ) 6 ), ethylaluminum (Al 2 (C 2 H 5 ) 6 ), aluminum acetate, and the like, and inorganic systems include aluminum nitrate, Aluminum chloride or the like can be suitably used.
これらの結晶析出剤は、有機アルミニウム化合物、特に、乳酸アルミニウムが、溶解度（25℃：30％）が高くて噴霧液を調製し易いため望ましい。この一次噴霧液の濃度は、要求特性（比表面積、圧縮強度等）に応じて、１〜30％の範囲で適宜調節する。噴霧液の態様は、通常、溶液とするが、エマルション、サスペンションであってもよい。 Among these crystal precipitation agents, organoaluminum compounds, particularly aluminum lactate, are desirable because they have high solubility (25 ° C .: 30%) and are easy to prepare a spray solution. The concentration of the primary spray solution is appropriately adjusted within a range of 1 to 30% according to required characteristics (specific surface area, compressive strength, etc.). The form of the spray liquid is usually a solution, but may be an emulsion or a suspension.
２）気孔形成剤（二次噴霧液）：
気孔形成剤としては、それぞれ非水溶性高分子（合成樹脂、天然ゴム又は合成ゴム）を水分散させたものが使用可能である。水を分散媒とするのは、乾燥速度の制御が容易なためである。また、該気孔形成剤は、一次噴霧後原料の粒子表面に対して濡れ性を有しない（接触角が鈍角）ものが好ましい。気孔形成剤の液滴が粒子表面で広がらず、液滴径を制御し易いためである。
2) Pore forming agent (secondary spray):
As the pore forming agent, water-insoluble polymers (synthetic resin, natural rubber or synthetic rubber) dispersed in water can be used. The reason why water is used as a dispersion medium is that the drying speed can be easily controlled. The pore-forming agent is preferably one that does not have wettability with respect to the particle surface of the raw material after primary spraying (contact angle is obtuse). This is because the pore-forming agent droplets do not spread on the particle surface and the droplet diameter can be easily controlled.
合成樹脂としては、熱可塑性でも熱硬化性でもよい。具体的には、焼成時の消失が円滑に行える、ポリ酢酸ビニル（ＰＶＡＣ）類（共重合体を含む。）、アクリル樹脂類（ポリアクリル酸エステル、ポリメタクリル酸エステル）、ノボラック型フェノール樹脂、ポリオレフィン・共重合ナイロン・共重合ポリエステル等を好適に使用できる。合成ゴムとしては、ポリイソプレン等を好適に使用できる。 The synthetic resin may be thermoplastic or thermosetting. Specifically, polyvinyl acetates (PVAC) (including copolymers), acrylic resins (polyacrylic acid ester, polymethacrylic acid ester), novolac-type phenolic resin, which can be smoothly eliminated during firing, Polyolefin, copolymerized nylon, copolymerized polyester and the like can be suitably used. As the synthetic rubber, polyisoprene can be preferably used.
これらのうちで、ＰＶＡＣ類が流動性の良好な噴霧液（エマルション）を調製し易くて望ましい。噴霧液の態様は、通常、エマルションとするが、ラテックス、サスペンションでもよい。 Among these, PVACs are desirable because they are easy to prepare a spray solution (emulsion) having good fluidity. The form of the spray liquid is usually an emulsion, but may be a latex or a suspension.
二次噴霧液の濃度は、エマルションの場合、１〜50％、望ましくは５〜15％とする。濃度が高すぎると、真球度の高い粒子からなる造粒体を得難くなる。濃度が低すぎると、適切な気孔径を造粒体の粒子に得ることが困難となる。 In the case of an emulsion, the concentration of the secondary spray liquid is 1 to 50%, desirably 5 to 15%. When the concentration is too high, it becomes difficult to obtain a granulated body composed of particles with high sphericity. If the concentration is too low, it is difficult to obtain an appropriate pore size in the granulated particles.
３）結合剤（三次噴霧液）：
結合剤としては、無機系・有機系を問わない。焼成により熱分解・揮散してアルミナ微粒子に実質的に残存しない有機系が望ましい。無機系の場合、残存すると触媒毒となるおそれがあり、アルミナ結晶の機能を阻害するおそれがある。有機系のうち、噴霧液の取扱い性に優れている水溶性有機高分子が望ましい。水溶性有機高分子としては、ポリビニルアルコール（ＰＶＡＬ）、ポリビニルアセタール・ポリビニルピロリドン、アクリルモノマー、セルロース誘導体（CMC・HPC・HPMC等）、澱粉等を好適に使用できる。
3) Binder (tertiary spray):
The binder may be inorganic or organic. An organic system which is thermally decomposed and volatilized by firing and does not substantially remain in the alumina fine particles is desirable. In the case of an inorganic system, if it remains, it may become a catalyst poison, which may hinder the function of the alumina crystal. Among organic systems, a water-soluble organic polymer that is excellent in handling of the spray liquid is desirable. As the water-soluble organic polymer, polyvinyl alcohol (PVAL), polyvinyl acetal / polyvinylpyrrolidone, acrylic monomer, cellulose derivative (CMC / HPC / HPMC, etc.), starch and the like can be suitably used.
この三次噴霧液の態様は、通常、水溶液とするが、適宜、極性溶剤を含有させて揮発度を調節してもよい。三次噴霧液の濃度は、１〜30％、望ましくは５〜１５％とする。濃度が高いと、真球度の高い造粒体を得難くなる。 The form of the tertiary spray liquid is usually an aqueous solution, but the volatility may be adjusted by appropriately adding a polar solvent. The concentration of the tertiary spray solution is 1 to 30%, preferably 5 to 15%. When the concentration is high, it becomes difficult to obtain a granulated body with high sphericity.
なお、有機系の場合において、上記気孔形成剤と同一又は同種樹脂を使用して、別位置で噴霧して結合剤とすることも可能である。 In the case of an organic system, it is possible to use the same or the same kind of resin as the pore forming agent and spray it at a different position to form a binder.
４）滑剤
滑剤としては、造粒体の流動性を増大させるものなら、無機系・有機系を問わない。造粒体に付着した後、焼成により熱分解・揮散して分離操作が不要な有機系滑剤が望ましい。有機系滑剤としては、合成樹脂微粉体や、脂肪酸エステル類、金属石鹸、炭化水素類（パラフィンワックス等）、等を使用可能である。これらの内で吸水率が低い（例えば、ASTMD570：0.5％以下）合成樹脂微粉体が望ましい。取扱い性が良好で流動性増大作用が安定しているためである。具体的には、ＰＭＭＡ、ポリエチレン、ポリエステル（ＰＥＴ）、等の微粉体を挙げることができる。これらの滑剤の平均粒径は、１〜50μmとする。
4) Lubricant As long as the lubricant increases the fluidity of the granulated body, it does not matter whether it is inorganic or organic. An organic lubricant that adheres to the granulated body and is pyrolyzed and volatilized by firing and does not require a separation operation is desirable. As the organic lubricant, synthetic resin fine powder, fatty acid esters, metal soaps, hydrocarbons (such as paraffin wax), and the like can be used. Of these, a synthetic resin fine powder having a low water absorption rate (for example, ASTM D570: 0.5% or less) is desirable. This is because the handleability is good and the fluidity increasing action is stable. Specific examples include fine powders such as PMMA, polyethylene, and polyester (PET). The average particle size of these lubricants is 1 to 50 μm.
本発明は、アルミナ微粉体からなる原料を、回転皿を備えた転動造粒機を用いて液剤噴霧しながら湿式造粒する造粒工程と、該造粒体を焼成する焼成工程とを含む、ことを前提とする。 The present invention includes a granulation step of wet granulating a raw material composed of fine alumina powder using a rolling granulator equipped with a rotating dish while spraying with a liquid agent, and a firing step of firing the granulated body. Assuming that.
本造粒工程は、下記1)一次噴霧工程、2)二次噴霧工程、3)三次噴霧工程、及び、4）整粒工程、の各副工程を含むものとする。 This granulation step includes the following sub-steps of 1) primary spraying step, 2) secondary spraying step, 3) tertiary spraying step, and 4) granulating step.
より具体的には、下記の如く行う。以下の説明で、噴霧量の単位：部／minは、アルミナ原料粉100部に対するものである。 More specifically, it is performed as follows. In the following description, the unit of spray amount: part / min is for 100 parts of the alumina raw material powder.
噴霧工程等に先立ち、一次噴霧液、二次噴霧液および三次噴霧液を調製する。また、それらの噴霧液を噴霧するために、各噴霧液とエアとを混合噴霧する二流体アトマイザー（噴霧器）を転動造粒機に３基付設する（図示せず。）。そして、本実施形態では、各噴霧器のノズルは、回転皿１７の排出部位（排出シュート１９）から斜め上方に伸びる傾斜直径（傾斜角度30〜45°）Ｄに沿って配する。ここで、噴霧ノズルを傾斜直径Ｄに沿って配するのは、噴霧器ノズル相互の離間距離（横（水平）方向および縦方向）を取りやすく、噴霧時の噴霧液相互に重なりが発生し難いためである。 Prior to the spraying process and the like, a primary spray solution, a secondary spray solution, and a tertiary spray solution are prepared. Further, in order to spray these spray solutions, three two-fluid atomizers (sprayers) for mixing and spraying each spray solution and air are attached to the rolling granulator (not shown). And in this embodiment, the nozzle of each sprayer is distribute | arranged along the inclination diameter (inclination angle 30-45 degrees) D which extends diagonally upwards from the discharge | emission site | part (discharge chute 19) of the rotating tray 17. FIG. Here, the spray nozzles are arranged along the inclined diameter D because the sprayer nozzles are easily separated from each other (lateral (horizontal) direction and vertical direction), and the spray liquids during spraying are unlikely to overlap each other. It is.
図例では、排出部位と対向した回転皿の外周部位近傍に配される原料投入部位側から、一次噴霧部位Ａ帯、二次噴霧部位Ｂ帯および三次噴霧部位Ｃ帯に、それぞれ、略同一幅で噴霧可能に噴霧ノズルを配する。このときの噴霧幅は、回転皿の内径が300ｍｍの場合、それぞれ、30〜70mmとする。 In the illustrated example, from the raw material charging site side disposed in the vicinity of the outer peripheral site of the rotating dish facing the discharge site, the primary spray site A zone, the secondary spray site B zone, and the tertiary spray site C zone have substantially the same width, respectively. A spray nozzle is arranged to enable spraying. The spray width at this time is 30 to 70 mm when the inner diameter of the rotating dish is 300 mm.
そして、回転皿を、回転数：10〜60min-１、望ましくは10〜45min-１の範囲で、傾斜角度：20〜70°、望ましくは40〜70°の範囲で、原料の平均粒径に対応させて回転させておく。これらの条件は、回転皿内の造粒状態等を監視しながら、適宜調節する。これらの回転数、傾斜角度範囲外では、原料、一次噴霧後原料、二次噴霧後原料、三次噴霧後原料を分級させながら転動循環させることが困難となる。 Then, the rotating dish is adjusted to the average particle diameter of the raw material at a rotation speed of 10 to 60 min −1 , preferably 10 to 45 min −1 and an inclination angle of 20 to 70 °, preferably 40 to 70 °. Rotate in correspondence. These conditions are appropriately adjusted while monitoring the granulation state in the rotating dish. Outside these rotational speeds and tilt angle ranges, it is difficult to roll and circulate while classifying the raw material, the raw material after primary spraying, the raw material after secondary spraying, and the raw material after tertiary spraying.
なお、粒子が濡れ状態（湿態時）では安息角が大きくなるため、傾斜角度も相対的に大きく設定する必要がある。 In addition, since the angle of repose becomes large when the particles are wet (in a wet state), it is necessary to set the inclination angle relatively large.
１）一次噴霧工程：
運転中の回転皿１７の原料投入部位（Ａ帯の上側部）に、アルミナ微粉体である原料（低ソーダアルミナ微粉）を投入する。
1) Primary spraying process:
The raw material (low soda alumina fine powder) which is fine alumina powder is charged into the raw material charging portion (the upper part of the A band) of the rotating dish 17 during operation.
原料は、回転皿１７の外周部（リム部１７ａ内側）に沿って一次転動循環する。すなわち、遠心力により回転皿の外周部に沿って、回転皿の下端外周部を経て回転皿の上端部を超えてＡ帯上方位置まで持ち上げられた後、重力が遠心力に勝ることにより反転して、大円弧を描いて、一次噴霧部位Ａ帯を経る一次転動循環をする。 The raw material circulates in a primary rolling manner along the outer peripheral portion of the rotating dish 17 (inside the rim portion 17a). In other words, after being lifted by the centrifugal force along the outer periphery of the rotating dish, through the lower end outer peripheral part of the rotating dish and beyond the upper end of the rotating dish to the position above the A band, the gravity is reversed by surpassing the centrifugal force. Then, a large circular arc is drawn, and the primary rolling circulation through the primary spray site A zone is performed.
該Ａ帯(一次転動循環の反転側部位、望ましくは反転直後部位）で、原料に対して、結晶析出剤（一次噴霧液）を一次噴霧する（図４（１）参照）。 In the zone A (reverse side portion of the primary rolling circulation, desirably a portion immediately after reversal), the crystal deposition agent (primary spray solution) is primarily sprayed on the raw material (see FIG. 4 (1)).
反転直後部位では、転動循環する原料の下方への広がりが殆どなく、粉体の集合密度が高いうちに噴霧でき、噴霧効率が良好となる（以下、二次噴霧・三次噴霧も同様である。）。 Immediately after the reversal, there is almost no downward spread of the raw material to be circulated, and the powder can be sprayed while the aggregate density of the powder is high, and the spray efficiency is good (the same applies to the secondary spray and tertiary spray below). .)
この一次噴霧の噴霧条件は、液滴径：10〜1000μm、望ましくは10〜300μm、単位時間噴霧量：0.01〜4.5部／min、望ましくは１〜３部／minの範囲で適宜選定する。合計噴霧量は、アルミナ原料粉100部に対して、１〜30部、望ましくは、１〜25部とする。 The spraying conditions for the primary spraying are appropriately selected within the range of droplet diameter: 10 to 1000 μm, desirably 10 to 300 μm, unit time spraying amount: 0.01 to 4.5 parts / min, desirably 1 to 3 parts / min. The total spray amount is 1 to 30 parts, preferably 1 to 25 parts, per 100 parts of the alumina raw material powder.
液滴径が小さすぎては、ドライミスト（濡れない液滴）となり、結晶析出剤が原料の各粒子を被覆し難くなる。逆に液滴径が大きすぎては、粒子相互の凝集現象が発生して造粒されやすくなり、気孔形成剤の各粒子に対する被覆がされ難くなり、気孔内にアルミナ析出結晶を形成し難くなる。いずれにしても、本発明の目的物（気孔内に析出結晶を有する多孔質造粒焼成体）を得難くなる。 If the droplet diameter is too small, it becomes dry mist (non-wetting droplet), and it becomes difficult for the crystal precipitation agent to coat each particle of the raw material. On the other hand, if the droplet diameter is too large, agglomeration phenomenon between particles occurs and granulation tends to occur, and it becomes difficult to coat each particle of the pore-forming agent, and it becomes difficult to form alumina precipitated crystals in the pores. . In any case, it is difficult to obtain the object of the present invention (porous granulated fired body having precipitated crystals in the pores).
また、単位時間噴霧量が少ないと作業時間が増加し、逆に、単位時間噴霧量が多いと凝集現象が発生して造粒されやすくなり、本発明の目的物（造粒体粒子の気孔内に析出結晶を有する多孔質造粒焼成体）を得難くなる。 In addition, when the spray amount per unit time is small, the working time increases, and conversely, when the spray amount per unit time is large, agglomeration phenomenon occurs and granulation tends to occur, and the object of the present invention (in the pores of the granulated particles). It is difficult to obtain a porous granulated fired body having precipitated crystals.
２）二次噴霧工程：
上記一次噴霧液が被覆された粒子からなる一次噴霧後原料（微粉体）は、一次転動循環の内側を二次転動循環する。すなわち、一次噴霧後原料は、結晶析出剤の被覆により重量が増大するため、重力の遠心力に勝る位置が、原料よりも手前側となり、Ａ帯の上方位置まで至らず反転し、中円弧を描いて、二次噴霧部位Ｂ帯を経る二次転動循環をする。
2) Secondary spraying process:
The primary sprayed raw material (fine powder) composed of particles coated with the primary spray liquid is circulated in a secondary rolling manner inside the primary rolling circulation. In other words, since the raw material after the primary spray increases in weight due to the coating of the crystal precipitation agent, the position superior to the centrifugal force of gravity is on the near side of the raw material, and does not reach the upper position of the A band, and the middle arc Draw and do secondary rolling circulation through secondary spray site B zone.
なお、一次噴霧液で被覆されなかった原料（粒子群）は、一次転動循環されてＡ帯に至って一次噴霧が繰り返えされる。 In addition, the raw material (particle group) which was not coat | covered with the primary spray liquid is primary-rolled and circulated, reaches A zone, and primary spray is repeated.
そして、上記Ｂ帯（二次転動循環の反転側部位）で、一次噴霧後原料に対して気孔形成剤（二次噴霧液）を二次噴霧する。 Then, the pore forming agent (secondary spray liquid) is secondarily sprayed on the raw material after the primary spraying in the B zone (reverse side portion of the secondary rolling circulation).
この気孔形成剤は、一次噴霧後原料の粒子相互を凝集させて一次造粒すると同時に、気孔形成剤の液滴径により粒子相互間の間隙を制御して、焼成工程で形成される気孔径の調節作用を担う（図４(２)）。 This pore-forming agent aggregates the particles of the raw material after the primary spraying and performs primary granulation, and at the same time, controls the gap between the particles by the droplet size of the pore-forming agent, and has the pore size formed in the firing step. Responsible for regulation (Fig. 4 (2)).
二次噴霧の噴霧条件は、液滴径：10〜1000μm、望ましくは10〜200μm、単位時間噴霧量：0.01〜4.5部／min、望ましくは１〜３部／minの範囲で適宜選定する。合計噴霧量は、アルミナ原料粉100部に対して、１〜30部、望ましくは、１〜25部とする。 The spraying conditions for the secondary spraying are appropriately selected within the range of droplet diameter: 10 to 1000 μm, desirably 10 to 200 μm, unit time spray amount: 0.01 to 4.5 parts / min, desirably 1 to 3 parts / min. The total spray amount is 1 to 30 parts, preferably 1 to 25 parts, per 100 parts of the alumina raw material powder.
気孔形成剤の単位時間噴霧量乃至合計噴霧量が少ないと、十分な気孔密度乃至気孔を造粒焼成体に得難い。逆に、単位時間噴霧量乃至合計噴霧量が多いと、気孔径のバラツキ度や気孔密度が高くなって造粒形状が異形乃至不揃いとなりやすい。 When the unit time spray amount or the total spray amount of the pore forming agent is small, it is difficult to obtain a sufficient pore density or pores in the granulated fired body. On the other hand, when the spray amount per unit time or the total spray amount is large, the degree of variation in pore diameter and the pore density increase, and the granulated shape tends to be irregular or irregular.
３）三次噴霧工程：
上記二次噴霧液が被覆された一次造粒体粒子からなる二次噴霧後原料は、二次転動循環の内側を、小円弧を描いて三次転動循環する。すなわち、二次噴霧後原料は、気孔形成剤の被覆および一次造粒により重量が増大するため、重力の遠心力に勝る位置が、一次噴霧後原料より手前側で反転して、Ｂ帯の上方位置まで至らず反転し、小円弧を描いて、三次噴霧部位Ｃ帯を経る三次転動循環をする。
3) Tertiary spraying process:
The raw material after the secondary spray composed of the primary granulated particles coated with the secondary spray liquid is subjected to the tertiary rolling circulation while drawing a small arc inside the secondary rolling circulation. That is, since the material after secondary spraying increases in weight due to the pore forming agent coating and primary granulation, the position superior to the centrifugal force of gravity is reversed on the near side from the material after primary spraying, and above the B band. It reverses without reaching the position, draws a small arc, and carries out the tertiary rolling circulation through the tertiary spray site C zone.
なお、二次噴霧液で被覆されなかった粒子群は、二次転動循環されてＢ帯に至り、二次噴霧が繰り返えされる。 In addition, the particle group which was not coat | covered with the secondary spray liquid is secondary-rolled and circulated to the B zone, and the secondary spray is repeated.
上記Ｃ帯（三次転動循環の反転側部位）で、二次噴霧後原料（一次造粒体）に対して結合剤（三次噴霧液）を三次噴霧する。 The binder (tertiary spray liquid) is subjected to tertiary spraying on the post-secondary spraying raw material (primary granulated body) in the C zone (reverse side part of the tertiary rolling circulation).
この結合剤は、二次噴霧後原料（一次造粒体）の造粒体粒子相互を結合させて二次造粒体（粗粒）とする。 This binder combines the granulated particles of the raw material after secondary spraying (primary granulated body) to form a secondary granulated body (coarse).
三次噴霧の噴霧条件は、液滴径：10〜1000μm、望ましくは10〜300μm、単位時間噴霧量：0.01〜4.５部／min、望ましくは１〜３部／minの範囲で適宜選定する。合計噴霧量は、アルミナ原料粉100部に対して、１〜30部、望ましくは、１〜15部とする。 The spraying conditions of the tertiary spraying are appropriately selected within the range of droplet diameter: 10 to 1000 μm, desirably 10 to 300 μm, unit time spray amount: 0.01 to 4.5 parts / min, desirably 1 to 3 parts / min. The total spray amount is 1 to 30 parts, preferably 1 to 15 parts, per 100 parts of the alumina raw material powder.
単位時間噴霧量乃至合計噴霧量が少なくては、十分な粒度（大きさ）の二次造粒体（粗粒）を得難く、かつ、造粒焼成体に網目状の気孔を得難い。逆に、単位時間噴霧量乃至合計噴霧量が多くても、造粒焼成体に網目状の気孔を得難い。 If the spray amount per unit time or the total spray amount is small, it is difficult to obtain a secondary granulated body (coarse grain) having a sufficient particle size (size), and it is difficult to obtain network-like pores in the granulated fired body. Conversely, even if the spray amount per unit time or the total spray amount is large, it is difficult to obtain network-like pores in the granulated fired body.
４)整粒工程：
上記三次噴霧液で一次造粒体の粒子が被覆された三次噴霧後原料は、三次転動循環と略重なるＣ帯の内側寄りを通過する転動循環をしながら、さらには三次噴霧も繰り返されて、造粒の成長が進行して所要径の二次造粒体（製品造粒体）に整粒される。その後、製品造粒体（二次造粒体）は排出シュート１９から排出される。
4) Granulation process:
The raw material after the tertiary spraying in which the particles of the primary granulated body are coated with the above-mentioned tertiary spraying liquid undergoes rolling circulation that passes near the inside of the C zone, which substantially overlaps with the tertiary rolling circulation, and further, the tertiary spraying is repeated. Thus, the growth of granulation proceeds and the secondary granulated product (product granulated product) having the required diameter is sized. Thereafter, the product granule (secondary granule) is discharged from the discharge chute 19.
なお、原料の追加投入に際して、前記滑剤を添加することが望ましい。各噴霧後原料が回転皿リムに付着するのを防止するとともに、原料の解砕がより円滑に行われるためである。このときの滑剤の添加量は、追加投入する原料100部に対して１〜50部、望ましくは10〜40部とする。 In addition, it is desirable to add the lubricant when the raw materials are added. This is because the raw material after spraying is prevented from adhering to the rotating dish rim, and the raw material is crushed more smoothly. The amount of lubricant added at this time is 1 to 50 parts, preferably 10 to 40 parts, with respect to 100 parts of the raw material to be additionally charged.
次に、上記で調製した製品造粒体を、電気炉等を用いて、焼成処理を行って焼成させる。 Next, the product granule prepared above is fired by firing using an electric furnace or the like.
ここで、前述のアルミナ微粒子を被覆する結晶析出剤が、噴霧後乾燥してアルミニウム化合物が析出成長し、さらに、焼成によりγアルミナさらにはαアルミナのアルミナ析出結晶となる。 Here, the crystal precipitating agent covering the above-mentioned alumina fine particles is sprayed and dried to precipitate and grow an aluminum compound. Further, by firing, it becomes γ-alumina and further alumina-precipitated crystals of α-alumina.
このときの焼成条件を下記する。 The firing conditions at this time are described below.
昇温速度：100〜700℃／ｈ、望ましくは200〜400℃／ｈとする。昇温速度が速すぎると、焼成体にクラックが発生しやすくなる。逆に遅すぎると、生産性が低下する。 Temperature increase rate: 100 to 700 ° C./h, desirably 200 to 400 ° C./h. If the heating rate is too fast, cracks are likely to occur in the fired body. Conversely, if it is too slow, productivity will decrease.
到達温度・保持時間は、γアルミナの析出結晶とする場合、500〜1300℃×１〜24ｈ、望ましくは600〜1100℃×１〜20ｈとする。また、αアルミナの析出結晶とする場合、1000〜2000℃×0.1〜３ｈ、望ましくは、1650〜1850℃×0.5〜１ｈとする。αアルミナの析出結晶とする焼成工程のモデルを図５に示す。 The ultimate temperature and holding time are set to 500 to 1300 ° C. × 1 to 24 hours, preferably 600 to 1100 ° C. × 1 to 20 hours, when γ-alumina is precipitated. Moreover, when setting it as the precipitation crystal | crystallization of (alpha) alumina, it is set to 1000-2000 degreeC x 0.1-3h, Preferably it is set to 1650-1850 degreeC x 0.5-1h. FIG. 5 shows a model of the firing process for forming α-alumina precipitated crystals.
この焼成工程において、図５Ａ・Ｂ・Ｃ・Ｄに示す如く、焼結が進行するにしたがって、造粒体粒子は縮み、気孔径も縮径し圧縮強度が漸増し、さらには、対向する析出結晶相互が融着して圧縮強度がさらに増大する。こうして、図１に示す如く、アルミナの析出結晶を内部に備えた気孔が造粒体粒子の断面全体に網目状に形成される。 In this firing step, as shown in FIGS. 5A, 5B, 5C, and 5D, as the sintering progresses, the granulated particles shrink, the pore diameter also shrinks, and the compressive strength gradually increases. The crystals are fused together to further increase the compressive strength. Thus, as shown in FIG. 1, pores having precipitated alumina crystals formed therein are formed in a mesh shape over the entire cross section of the granulated particles.
以上、原料がアルミナ微粉体である場合を例に採り説明したが、本発明は、アルミナ微粒体をセラミック微粉体に替えた下記構成のセラミック微粉焼成体(1)及びその製造方法(2)にも及ぶものである。 As described above, the case where the raw material is an alumina fine powder has been described as an example, but the present invention relates to a ceramic fine powder fired body (1) having the following configuration in which the alumina fine powder is replaced with a ceramic fine powder, and a method for producing the same (2). It also extends.
(1）無数のセラミック粒子同士が、主として連通する気孔を造粒体粒子の断面全体に網目状に残存させて固結してなる多孔質造粒焼成体であって、前記気孔は、その内径が気孔形成剤の液滴径で制御されているとともに、その内面に無数のアルミナ析出結晶を有していることを特徴とする。 (1) A porous granulated fired body in which innumerable ceramic particles are mainly consolidated by leaving pores that communicate with each other in the entire cross section of the granulated particles, the pores having an inner diameter thereof Is controlled by the droplet diameter of the pore-forming agent and has innumerable alumina precipitated crystals on its inner surface.
(2) 上記多孔質造粒焼結体の製造方法であって、
セラミック微粉体からなる原料を、回転皿を備えた転動造粒機を用いて液剤噴霧しながら湿式造粒する造粒工程と、該造粒体を焼成する焼成工程とを含み、
前記造粒工程は、
1)回転皿の斜め下方部に位置する排出部に対向する上方部側から投入され、回転皿の外周部に沿って一次転動循環をする原料に対して、結晶析出剤を一次噴霧する工程、
2)前記一次転動循環の内側を二次転動循環する一次噴霧後原料に対して気孔形成剤を二次噴霧する工程、
3)前記二次転動循環の内側を三次転動循環する二次噴霧後原料に対して、結合剤を三次噴霧する工程、及び、
4)三次噴霧後原料を、さらなる転動循環により造粒成長を進行させて所要径の造粒体に整粒する工程、
の各副工程を含み、
前記一次・二次・三次噴霧を、それぞれ、一次・二次・三次転動循環する反転側部位で行う、ことを特徴とする。
(2) A method for producing the porous granulated sintered body,
Including a granulation step of wet granulation while spraying a liquid material using a rolling granulator equipped with a rotating dish with a raw material made of ceramic fine powder, and a firing step of firing the granulated body,
The granulation step includes
1) A step of primary spraying of a crystal precipitation agent on a raw material which is introduced from an upper part side facing a discharge part located at an obliquely lower part of a rotating dish and performs primary rolling circulation along an outer peripheral part of the rotating dish. ,
2) a step of secondary spraying the pore-forming agent on the raw material after the primary spraying that undergoes secondary rolling circulation inside the primary rolling circulation;
3) The step of tertiary spraying the binder to the secondary sprayed raw material that undergoes tertiary rolling circulation inside the secondary rolling circulation; and
4) A step of granulating the raw material after the third spraying by further rolling circulation to make a granulated body of a required diameter,
Each sub-process of
The primary / secondary / tertiary spraying is performed on the reversing side portions where the primary, secondary, and tertiary rolling circulate, respectively.
上記原料（微粉体）となるセラミックとしては、酸化マグネシウム（ＭｇＯ）、酸化ジルコニウム（ＺｒＯ２）、酸化チタン（ＴｉＯ２）、酸化カルシウム（ＣａＯ）、酸化ベリリウム（ＢｅＯ）等を挙げることができる。 Examples of the ceramic that is the raw material (fine powder) include magnesium oxide (MgO), zirconium oxide (ZrO 2 ), titanium oxide (TiO 2 ), calcium oxide (CaO), and beryllium oxide (BeO).
以下、本発明の効果を確認するために比較例とともに行った実施例について説明する。なお、転動造粒機は、実施例・比較例ともに、内径300mmのパン型の回転皿を備えたものを使用した。そして、回転皿１５における各噴霧帯であるＡ帯、Ｂ帯及びＣ帯は前述の図２に示す通りとし、各噴霧帯の幅は、50ｍｍとした。 Examples carried out together with comparative examples to confirm the effects of the present invention will be described below. The rolling granulator used in both the examples and comparative examples was equipped with a pan-type rotating dish having an inner diameter of 300 mm. The A-band, B-band, and C-band, which are the spray bands in the rotating dish 15, are as shown in FIG. 2, and the width of each spray band is 50 mm.
また、使用原料および薬剤、仕様は、それぞれ下記の通りである。 In addition, the raw materials used, the chemicals, and the specifications are as follows.
１）原料
・仮焼アルミナ微粉体（低ソーダアルミナ）・・・平均粒径：2.５μm、Ｎａ２Ｏ：0.０８％、比表面積：1.４ｇ／ｍ２
・活性アルミナ・・・平均粒径：1.5μm、Ｎａ２Ｏ：0.45％、比表面積：1.５ｇ／ｍ２
1) Raw materials-Calcined alumina fine powder (low soda alumina) ... average particle diameter: 2.5 µm, Na 2 O: 0.08%, specific surface area: 1.4 g / m 2
Active alumina: average particle size: 1.5 μm, Na 2 O: 0.45%, specific surface area: 1.5 g / m 2
２）薬剤
・結晶析出剤（一次噴霧液）・・・乳酸アルミニウムの30％水溶液、
・気孔形成剤（二次噴霧液）・・・ＰＶＡＣ（平均粒径：10μm）の10％エマルション、ＰＶＡＣ粒径：1μm
・結合剤（三次噴霧液）・・・ＰＶＡＬの10％水溶液、
・滑剤・・・ＰＭＭＡ微粉体（平均粒径５μm）
2) Drug ・ Crystal precipitation agent (primary spray solution) ... 30% aqueous solution of aluminum lactate,
・ Porosity forming agent (secondary spray solution): 10% emulsion of PVAC (average particle size: 10 μm), PVAC particle size: 1 μm
・ Binder (tertiary spray): 10% aqueous solution of PVAL,
・ Lubricant: PMMA fine powder (average particle size 5μm)
＜実施例＞
傾斜角度55°に調節され回転数25min−１で回転する回転皿に、原料である低ソーダアルミナ100ｇを原料投入部位（Ａ帯の上方）から投入した後、回転皿を起動させ、適正な転動循環が原料粉体に発生するように回転数及び傾斜角度を調節する。調節範囲は、前者：25〜35min−１及び後者：55〜62°とした。
<Example>
After feeding 100 g of low-soda alumina, which is a raw material, from a raw material charging site (above A band) into a rotating pan adjusted to an inclination angle of 55 ° and rotating at a rotational speed of 25 min −1 The rotational speed and the tilt angle are adjusted so that dynamic circulation occurs in the raw material powder. The adjustment ranges were the former: 25 to 35 min −1 and the latter: 55 to 62 °.
１）一次転動循環する原料に対して、Ａ帯で一次噴霧液を噴霧した。このとき、液滴径が10μmになるように噴霧圧・単位時間噴霧量を調節して噴霧した。このときの合計噴霧量は、原料100部に対して20部に設定した。そして、本実施例では単位時間噴霧量2.5部／minとしたので、噴霧合計時間は８分となる。 1) The primary spray solution was sprayed in the A zone on the raw material that undergoes primary rolling circulation. At this time, spraying was carried out while adjusting the spray pressure and the spray amount per unit time so that the droplet diameter was 10 μm. The total spray amount at this time was set to 20 parts with respect to 100 parts of the raw material. In this embodiment, since the spray amount per unit time is 2.5 parts / min, the total spray time is 8 minutes.
２）二次転動循環する一次噴霧後原料に対して、Ｂ帯で、気孔形成剤（二次噴霧液）を噴霧した。このときの二次噴霧液の合計噴霧量は、原料100部に対して20部に設定した。なお、二次噴霧液の単位時間噴霧量を2.5部／minに設定して、前記一次噴霧液の合計噴霧時間８分と対応するようにした。同時噴霧して連続造粒を可能とするためである。 2) A pore-forming agent (secondary spray solution) was sprayed in the B zone on the raw material after the primary spraying that was subjected to secondary rolling circulation. The total spray amount of the secondary spray liquid at this time was set to 20 parts with respect to 100 parts of the raw material. The unit spray amount of the secondary spray solution was set at 2.5 parts / min so as to correspond to the total spray time of 8 minutes of the primary spray solution. This is to enable continuous granulation by simultaneous spraying.
３）三次転動循環する二次噴霧後原料に対して、Ｃ帯で結合剤（三次噴霧液）を噴霧した。このときの結合剤の合計噴霧量は、次の整粒工程を含めて、原料100部に対して10部（固形分換算）に設定した。なお、三次噴霧液の単位時間噴霧量を2.５部／minに設定して、前記一次・二次噴霧液の合計噴霧時間８分と対応するようにした。同時噴霧して連続造粒を可能とするためである。 3) The binder (tertiary spray liquid) was sprayed in the C zone to the secondary sprayed raw material that circulates in a tertiary rolling manner. The total spray amount of the binder at this time was set to 10 parts (in terms of solid content) with respect to 100 parts of the raw material including the next granulation step. In addition, the unit time spray amount of the tertiary spray solution was set to 2.5 parts / min so as to correspond to the total spray time of the primary and secondary spray solutions of 8 minutes. This is to enable continuous granulation by simultaneous spraying.
４）三次噴霧後原料は、Ｃ帯の内側寄りを経る転動循環を繰り返して、造粒の成長が所要の造粒径（平均粒径：２mm）となるまで整粒する。 4) The material after the tertiary spraying is tumbled and circulated through the inner side of the C band, and is sized until the growth of granulation reaches the required granulated particle size (average particle size: 2 mm).
なお、この整粒の最終段階である二次造粒完了の直前、本実施例では10分前に、原料20部に滑剤５部を添加したものを、単位時間投入量2.5部／minとなるように原料投入部位から分割投入した。 In addition, immediately before the completion of the secondary granulation, which is the final stage of the sizing, in this example, 10 parts before 10 minutes before adding 5 parts of lubricant to the raw material, the unit time input is 2.5 parts / min. In this way, it was dividedly charged from the raw material charging site.
上記転動造粒の運転中において、回転皿内の温度は28℃以下18℃以上になるように、噴霧液の温度・単位時間噴霧量を調節した。温度が高すぎても低すぎても、噴霧液の揮発速度が速すぎたり、遅すぎたりして、造粒が円滑に行われないためである。なお、蒸発熱により回転皿内の温度が低下するために、回転皿の裏側位置に電熱ヒータを非接触式で配した。 During the operation of the rolling granulation, the temperature of the spray liquid and the spray amount per unit time were adjusted so that the temperature in the rotating dish was 28 ° C. or lower and 18 ° C. or higher. This is because if the temperature is too high or too low, the volatilization rate of the spray liquid is too fast or too slow, and granulation is not performed smoothly. In addition, in order to reduce the temperature in a rotating tray by evaporative heat, the electric heater was arrange | positioned by the non-contact type in the back side position of the rotating tray.
次に、こうして調製した湿式造粒体を、昇温速度300℃／ｈで到達温度900℃まで昇温させ３ｈ保持後、さらに、同一昇温速度で到達温度1650℃まで昇温させ0.5ｈ保持して、焼成体とした。 Next, the wet granulate thus prepared is heated to an ultimate temperature of 900 ° C. at a heating rate of 300 ° C./h and held for 3 hours, and further heated to an ultimate temperature of 1650 ° C. at the same heating rate and held for 0.5 h. Thus, a fired body was obtained.
＜比較例１＞
上記実施例において、原料として、活性アルミナ（Ｎａ２Ｏ：0.45％、中心粒径1.５μm、比表面積200ｍ２／ｇ）100ｇを投入し、該原料を同一条件で転動循環させながら、一次・二次噴霧被覆をせずに、結合剤（ＰＶＡＬ10％水溶液）をＡ帯で単位時間噴霧量2５ｇ(固形分2.５ｇ）／minで合計噴霧量100ｇ（固形分10ｇ）となるように合計時間４min噴霧した。
<Comparative Example 1>
In the above embodiment, 100 g of activated alumina (Na 2 O: 0.45%, center particle size 1.5 μm, specific surface area 200 m 2 / g) is added as a raw material, -Without secondary spray coating, the binder (PVAL 10% aqueous solution) is totaled so that the total spray amount is 100 g (solid content 10 g) at the A band at a unit time spray amount 25 g (solid content 2.5 g) / min. Sprayed for 4 minutes.
こうして調製した湿式造粒体を、実施例と同様の条件で焼成させた。 The wet granulate thus prepared was fired under the same conditions as in the examples.
＜比較例２＞
比較例１において、原料として、実施例に使用した低ソーダアルミナを用いて、同様にして転動造粒した湿式造粒体を、同様の条件で焼成させた。
<Comparative Example 2>
In Comparative Example 1, a wet granulated material that was tumbled and granulated in the same manner using the low-soda alumina used in the examples as a raw material was fired under the same conditions.
こうして調製した実施例・比較例１，２の各比表面積、ソーダ成分および圧縮強度(粒子強度）を計測したので表１に示す。 Table 1 shows the specific surface areas, soda components and compressive strength (particle strength) of Examples and Comparative Examples 1 and 2 thus prepared.
実施例および比較例１・２との結果から、下記のことが判明した。 From the results of Examples and Comparative Examples 1 and 2, the following was found.
（１）実施例の粒子強度は、活性アルミナ粉体を原料とする焼成体（比較例１）より格段に高いことはもとより、実施例と同じ低ソーダアルミナを原料とする従来法による焼成体（比較例２）と略同等であった。気孔内のアルミナ析出結晶の存在により、高温焼成（焼結）によって塞がれなかったためと推定される。 (1) The particle strength of the example is notably higher than the fired body made of activated alumina powder as a raw material (Comparative Example 1), but also the fired body made by the conventional method using the same low soda alumina as the raw material (Example 1). It was substantially equivalent to Comparative Example 2). It is presumed that it was not blocked by high-temperature firing (sintering) due to the presence of alumina precipitated crystals in the pores.
（２）実施例の比表面積は、比較例１より若干高いとともに、実施例と同じ低ソーダアルミナを原料とする従来法による焼成体（比較例２）より格段に大きい。多孔質であるとともに気孔内面にアルミナ析出結晶が存在するためであると推定される。また、比較例１の比表面積の低下は、活性アルミナの気孔が焼結により塞がれたためと推定される。 (2) The specific surface area of the example is slightly higher than that of Comparative Example 1, and is significantly larger than that of a fired body obtained by the conventional method using the same low soda alumina as that of the Example (Comparative Example 2). It is presumed that this is due to the presence of alumina precipitated crystals on the pore inner surface as well as the porosity. The decrease in the specific surface area of Comparative Example 1 is presumed to be due to the pores of activated alumina being blocked by sintering.
（３）実施例のソーダ成分は原料の約１／４で、比較例１より格段に少ないことは勿論、比較例２よりもさらに低くなっていた。実施例・比較例2におけるソーダ成分の低下は、高温焼成（焼結）によりソーダ成分が揮発したためと推定される。 (3) The soda component of the example was about ¼ of the raw material and was much lower than Comparative Example 2 as well as being significantly less than Comparative Example 1. The decrease in the soda component in Example / Comparative Example 2 is presumed to be due to volatilization of the soda component by high-temperature firing (sintering).
そして、各実施例・比較例の造粒体の走査型電子顕微鏡（ＳＥＭ）写真を低倍率及び高倍率で撮影した。それらのＳＥＭ写真を図６（Ａ）・（Ｂ）・（Ｃ）に示す。図６のＳＥＭ写真から、本発明の実施例は、比較例１・２と真球度は余り変わらないが、比較例１・２に比して気孔密度がより均質であることが分かる。 And the scanning electron microscope (SEM) photograph of the granulated body of each Example and a comparative example was image | photographed with low magnification and high magnification. Those SEM photographs are shown in FIGS. 6 (A), (B), and (C). From the SEM photograph in FIG. 6, it can be seen that the sphericity of the example of the present invention is not so different from that of Comparative Examples 1 and 2, but the pore density is more uniform than that of Comparative Examples 1 and 2.
１１ 多孔質造粒焼成体の粒子
１３ 気孔
１５ アルミナ析出結晶
11 Particles of porous granulated fired body 13 Pore 15 Alumina precipitated crystal
Claims (10)
アルミナ微粉体からなる原料を、回転皿を備えた転動造粒機を用いて液剤噴霧しながら湿式造粒する造粒工程と、該造粒体を焼成する焼成工程とを含み、
前記造粒工程は、
1)回転皿の斜め下方部に位置する排出部に対向する上方部側から投入され、回転皿の外周部に沿って一次転動循環をする原料に対して、結晶析出剤を一次噴霧する工程、
2)前記一次転動循環の内側を二次転動循環する一次噴霧後原料に対して気孔形成剤を二次噴霧する工程、
3)前記二次転動循環の内側を三次転動循環する二次噴霧後原料に対して、結合剤を三次噴霧する工程、及び、
4)三次噴霧後原料を、さらなる転動循環により造粒成長を進行させて所要径の造粒体に整粒する工程、
の各副工程を含み、
前記一次・二次・三次噴霧を、それぞれ、一次・二次・三次転動循環する反転側部位で行う、
ことを特徴とする多孔質造粒焼成体の製造方法。 A method for producing a porous granulated fired body according to any one of claims 1 to 4,
A raw material comprising alumina fine powder, including a granulation step of wet granulation while spraying with a liquid agent using a rolling granulator equipped with a rotating dish, and a firing step of firing the granulated body,
The granulation step includes
1) A step of primary spraying of a crystal precipitation agent on a raw material which is introduced from an upper part side facing a discharge part located at an obliquely lower part of a rotating dish and performs primary rolling circulation along an outer peripheral part of the rotating dish. ,
2) a step of secondary spraying the pore-forming agent on the raw material after the primary spraying that undergoes secondary rolling circulation inside the primary rolling circulation;
3) The step of tertiary spraying the binder to the secondary sprayed raw material that undergoes tertiary rolling circulation inside the secondary rolling circulation; and
4) A step of granulating the raw material after the third spraying by further rolling circulation to make a granulated body of a required diameter,
Each sub-process of
The primary / secondary / tertiary spraying is performed on the reversing side portion where the primary / secondary / tertiary rolling circulation is performed, respectively.
A method for producing a porous granulated fired body.
セラミック微粉体からなる原料を、回転皿を備えた転動造粒機を用いて液剤噴霧しながら湿式造粒する造粒工程と、該造粒体を焼成する焼成工程とを含み、
前記造粒工程は、
1)回転皿の斜め下方部に位置する排出部に対向する上方部側から投入され、回転皿の外周部に沿って一次転動循環をする原料に対して、結晶析出剤を一次噴霧する工程、
2)前記一次転動循環の内側を二次転動循環する一次噴霧後原料に対して気孔形成剤を二次噴霧する工程、
3)前記二次転動循環の内側を三次転動循環する二次噴霧後原料に対して、結合剤を三次噴霧する工程、及び、
4)三次噴霧後原料を、さらなる転動循環により造粒成長を進行させて所要径の造粒体に整粒する工程、
の各副工程を含み、
前記一次・二次・三次噴霧を、それぞれ、一次・二次・三次転動循環する反転側部位で行う、
ことを特徴とする多孔質造粒焼成体の製造方法。 A method for producing a porous granulated fired body according to claim 9,
Including a granulation step of wet granulation while spraying a liquid material using a rolling granulator equipped with a rotating dish with a raw material made of ceramic fine powder, and a firing step of firing the granulated body,
The granulation step includes
1) A step of primary spraying of a crystal precipitation agent on a raw material which is introduced from an upper part side facing a discharge part located at an obliquely lower part of a rotating dish and performs primary rolling circulation along an outer peripheral part of the rotating dish. ,
2) a step of secondary spraying the pore-forming agent on the raw material after the primary spraying that undergoes secondary rolling circulation inside the primary rolling circulation;
3) The step of tertiary spraying the binder to the secondary sprayed raw material that undergoes tertiary rolling circulation inside the secondary rolling circulation; and
4) A step of granulating the raw material after the third spraying by further rolling circulation to make a granulated body of a required diameter,
Each sub-process of
The primary / secondary / tertiary spraying is performed on the reversing side portion where the primary / secondary / tertiary rolling circulation is performed, respectively.
A method for producing a porous granulated fired body.
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