JPH01298018A - Production of alumina having high purity - Google Patents
Production of alumina having high purityInfo
- Publication number
- JPH01298018A JPH01298018A JP12565388A JP12565388A JPH01298018A JP H01298018 A JPH01298018 A JP H01298018A JP 12565388 A JP12565388 A JP 12565388A JP 12565388 A JP12565388 A JP 12565388A JP H01298018 A JPH01298018 A JP H01298018A
- Authority
- JP
- Japan
- Prior art keywords
- alumina
- firing
- raw material
- purity
- temperature
- 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
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 154
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 239000002994 raw material Substances 0.000 claims abstract description 45
- 239000002245 particle Substances 0.000 claims abstract description 42
- 239000012535 impurity Substances 0.000 claims abstract description 36
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 26
- 239000012298 atmosphere Substances 0.000 claims abstract description 25
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims abstract description 9
- 230000001590 oxidative effect Effects 0.000 claims abstract description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000010304 firing Methods 0.000 claims description 60
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 13
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 8
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 229910001948 sodium oxide Inorganic materials 0.000 claims description 6
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 5
- 239000000395 magnesium oxide Substances 0.000 claims description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 4
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 4
- 238000000034 method Methods 0.000 abstract description 43
- 238000001354 calcination Methods 0.000 abstract description 15
- 229910052681 coesite Inorganic materials 0.000 abstract 1
- 229910052906 cristobalite Inorganic materials 0.000 abstract 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract 1
- 239000000377 silicon dioxide Substances 0.000 abstract 1
- 235000012239 silicon dioxide Nutrition 0.000 abstract 1
- 229910052682 stishovite Inorganic materials 0.000 abstract 1
- 229910052905 tridymite Inorganic materials 0.000 abstract 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 33
- 229910002804 graphite Inorganic materials 0.000 description 19
- 239000010439 graphite Substances 0.000 description 19
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 17
- 230000008569 process Effects 0.000 description 14
- 229910052799 carbon Inorganic materials 0.000 description 11
- 238000004131 Bayer process Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 239000000919 ceramic Substances 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 239000007787 solid Substances 0.000 description 7
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 6
- 229940024545 aluminum hydroxide Drugs 0.000 description 6
- 235000013980 iron oxide Nutrition 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 101100348017 Drosophila melanogaster Nazo gene Proteins 0.000 description 5
- 239000006229 carbon black Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 239000000654 additive Substances 0.000 description 4
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 239000010419 fine particle Substances 0.000 description 4
- 238000009413 insulation Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- -1 polyethylene Polymers 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003082 abrasive agent Substances 0.000 description 3
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000008187 granular material Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 229940037003 alum Drugs 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229940063656 aluminum chloride Drugs 0.000 description 2
- 229940024546 aluminum hydroxide gel Drugs 0.000 description 2
- SMYKVLBUSSNXMV-UHFFFAOYSA-K aluminum;trihydroxide;hydrate Chemical compound O.[OH-].[OH-].[OH-].[Al+3] SMYKVLBUSSNXMV-UHFFFAOYSA-K 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011362 coarse particle Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000010494 dissociation reaction Methods 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- SZIFAVKTNFCBPC-UHFFFAOYSA-N 2-chloroethanol Chemical compound OCCCl SZIFAVKTNFCBPC-UHFFFAOYSA-N 0.000 description 1
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 229920000265 Polyparaphenylene Polymers 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- JGDITNMASUZKPW-UHFFFAOYSA-K aluminium trichloride hexahydrate Chemical compound O.O.O.O.O.O.Cl[Al](Cl)Cl JGDITNMASUZKPW-UHFFFAOYSA-K 0.000 description 1
- 229940009861 aluminum chloride hexahydrate Drugs 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 229910001570 bauxite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000010000 carbonizing Methods 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001648 diaspore Inorganic materials 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 208000018459 dissociative disease Diseases 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910001679 gibbsite Inorganic materials 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000007770 graphite material Substances 0.000 description 1
- 230000009422 growth inhibiting effect Effects 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920005615 natural polymer Polymers 0.000 description 1
- 239000000615 nonconductor Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 125000002524 organometallic group Chemical group 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000005720 sucrose Substances 0.000 description 1
- 229920001059 synthetic polymer Polymers 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/46—Purification of aluminium oxide, aluminium hydroxide or aluminates
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、高純度アルミナ並びに微粒高純度アルミナの
製造方法に関すものであり、殊に、バイヤープロセス法
により製造された水酸化アルミニウム及びこの水酸化ア
ルミニウムを加熱処理して得られた中間アルミナやα−
アルミナ等を原料アルミナとして高純度アルミナ並びに
微粒高純度アルミナを製造するのに好適な方法に関する
ものである。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to high-purity alumina and a method for producing fine-grained high-purity alumina. Intermediate alumina and α- obtained by heat treating aluminum hydroxide
The present invention relates to a method suitable for producing high-purity alumina and fine-grained high-purity alumina using alumina or the like as a raw material alumina.
（従来技術とその問題点）
アルミナは、物理的・化学的性質が優れているので従来
からセラミックス用・触媒用・医薬品用・研削材用・電
気絶縁体用等種々の用途に使用されて来た。それらは、
バイヤープロセス法による大量生産方式で安定した品質
のものが安価に供給されたことによるところが大きい。(Prior art and its problems) Alumina has excellent physical and chemical properties, so it has been used for various purposes such as ceramics, catalysts, pharmaceuticals, abrasives, and electrical insulators. Ta. They are,
This is largely due to the fact that products of stable quality were supplied at low prices through mass production using the Bayer process method.
一方、近年ファインセラミックス市場が拡大し、そこで
は所望特性を充足させるため原材料に高純度化と微粒子
化を要求するようになっている。On the other hand, the fine ceramics market has expanded in recent years, and in order to satisfy desired characteristics, raw materials are required to have higher purity and finer particles.
アルミナにおいても、高純度化と微粒子化とを図ること
によって、低温焼結性・化学的安定性・機械加工性・組
織均一性等が向上することが知られており、高品質のセ
ラミックス工具・ＩＣ基板・特殊研摩材・人造宝石原料
・透光性アルミナ・各種添加材等に適用分野を拡大して
いる。It is also known that alumina can be improved in low-temperature sinterability, chemical stability, machinability, structure uniformity, etc. by making it highly purified and fine-grained, resulting in high-quality ceramic tools and Application fields are expanding to include IC substrates, special abrasives, raw materials for artificial jewelry, translucent alumina, and various additives.
このような新規分野でのアルミナとしては、純度が９９
．９％〜９９．９９％で、平均粒子径が０．１〜１．０
μｍ程度の微粒高純度アルミナが用いられており、従来
用途でもこの種の品質のものを使用することにより、特
性レベルをより向上させることができる。Alumina used in this new field has a purity of 99.
．． 9% to 99.99%, average particle size 0.1 to 1.0
Fine particles of high purity alumina on the order of μm are used, and by using this type of quality alumina even in conventional applications, the level of properties can be further improved.
しかるに、バイヤープロセス法で得られるアルミナの純
度は通常９９％程度である。その中、金属酸化物不純物
としては、酸化ナトリウム（Ｎａ、０） ２０００〜６
０００ ＰＰＭ、酸化鉄（ＦｅｚＯｉ） １００〜５０
０ＰＰＭ、酸化けい素（Ｓｉ（ｈ） １００〜７００
ＰＰＭ、酸化カルシウム（Ｃａｂ） ５０〜５００
ＰＰＭ程度含有される。又、金属アルミニウムを塩酸
で処理して得た塩化アルミニウムを焼成して得られたア
ルミナは、酸化マグネシウム（Ｍｇ０）が５０〜１００
ＯＰＰガ含有されることがある。そのため、この種の新
規分野にバイヤー法アルミナ等を適用できるようにする
ためには、精製工程が必要となる。However, the purity of alumina obtained by the Bayer process is usually about 99%. Among them, as metal oxide impurities, sodium oxide (Na, 0) 2000-6
000 PPM, iron oxide (FezOi) 100-50
0PPM, silicon oxide (Si(h) 100-700
PPM, calcium oxide (Cab) 50-500
Contains approximately PPM. In addition, alumina obtained by firing aluminum chloride obtained by treating aluminum metal with hydrochloric acid has a magnesium oxide (Mg0) content of 50 to 100.
May contain OPP moth. Therefore, in order to be able to apply Bayer process alumina etc. to this type of new field, a refining process is required.
従来、この種の目的のため、例えば、低ソーダアルミナ
を得るものとして特開昭５６−１４９３１９号公報等に
開示・記載されている方法が提案されているが、ソーダ
除去剤で処理した後焼成処理するなど複雑な処理工程を
経るものであり、コスト的に問題がある。Conventionally, for this purpose, a method disclosed and described in JP-A-56-149319 etc. has been proposed for obtaining low-soda alumina, but the method involves calcination after treatment with a soda removing agent. It requires complicated processing steps such as processing, which poses a problem in terms of cost.
一方、高純度アルミナを得る方法として、明ばん熱分解
法・有機金属加水分解法・エチレンクロルヒドリン法・
火花放電法等が提案（例えば、雑誌「セラミックスＪ
ＶＯＬ、 １７Ｔｈ９． ７６４〜７７０頁或は日本セ
ラミックス協会の昭和６２年１２月３日付原料部会講演
会資料中の「高純度アルミナの粉体特性と機能性」 （
伊沢）等を参照）されているが、原料自体が高純度のも
のを用いたり、プロセスが複雑であるなど、コスト的問
題が同様にある。On the other hand, methods for obtaining high-purity alumina include the alum pyrolysis method, organometallic hydrolysis method, ethylene chlorohydrin method,
Spark discharge method etc. have been proposed (for example, in the magazine "Ceramics J
VOL, 17Th9. Pages 764 to 770 or "Powder properties and functionality of high-purity alumina" in materials for the December 3, 1986 Raw Materials Subcommittee lecture of the Japan Ceramics Association (
(see Izawa et al.), but there are similar cost problems, such as the use of highly pure raw materials and the complicated process.
又、微粒状原料アルミナを加熱焼成処理する場合、高温
下の固体拡散による粒子成長が発生し、５μｍ以下、特
に粒径が重要因子とされる１、０μｍ以下の製品を所望
するとき粗粒化が顕著な問題となる。即ち、−旦粗粒化
が発生すると後工程として粉砕工程が必要となるので、
生産効率が著るしく低下しコストの上昇を招くため好ま
しくない。又、粉砕手段では充填性に優れた真球度の高
い微粒アルミナを得ることが困難であるという新たな問
題も生じる。In addition, when fine-grain raw material alumina is heated and fired, particle growth occurs due to solid diffusion at high temperatures, and when a product of 5 μm or less, especially 1.0 μm or less, where particle size is an important factor, is desired, coarse graining is required. becomes a significant problem. In other words, once coarsening occurs, a crushing step is required as a post-process.
This is not preferable because production efficiency is significantly reduced and costs are increased. In addition, a new problem arises in that it is difficult to obtain fine alumina particles with excellent filling properties and high sphericity using the crushing means.
一方、個々の不純物に於ける問題点としては、その用途
に応じて種々の問題を派生するが、例えば、酸化ナトリ
ウム（ソーダ）は電気絶縁性を低下させ、酸化鉄は基材
を着色させる問題があり、酸化けい素は焼結体の化学的
安定性を阻害し雰囲気耐食性を低下させ、酸化マグネシ
ウム及び酸化カルシウムは焼結性を低下させるなどの問
題があるので、可能な限りその含有量が低い程、アルミ
ナの特性を良好なものとすることができる。又、添加剤
として使用される場合には、その添加による不純物の混
入汚染を最小限に抑えることができる。On the other hand, there are various problems associated with individual impurities depending on their usage. For example, sodium oxide (soda) reduces electrical insulation, and iron oxide colors the base material. However, silicon oxide inhibits the chemical stability of the sintered body and reduces atmospheric corrosion resistance, and magnesium oxide and calcium oxide reduce sinterability, so the content should be reduced as much as possible. The lower the value, the better the properties of alumina can be. Furthermore, when used as an additive, contamination caused by impurities can be minimized.
（発明の目的）
本発明は、上記課題に対応出来る手段として、常法で得
られる純度９９％程度のアルミナから高純度アルミナを
製造する方法を提案するものであり、殊に減圧下の高温
加熱処理によって金属酸化物不純物を熱分解させその分
解生成物を系外に除去することによって高純度アルミナ
を製造する方法を提案するものである。しかも、除去対
象不純物成分に応じて単に焼成条件の調整により対応し
得る方法を提案するものである。(Objective of the Invention) The present invention proposes a method for producing high-purity alumina from alumina with a purity of about 99% obtained by a conventional method as a means to address the above-mentioned problems. This paper proposes a method for producing high-purity alumina by thermally decomposing metal oxide impurities and removing the decomposition products from the system. Moreover, the present invention proposes a method that can be handled simply by adjusting the firing conditions depending on the impurity component to be removed.
更に、前記方法を微粒アルミナにも適用できるように焼
成時の粒子成長を抑制する手段を更に付加した方法を提
案するものである。Furthermore, the present invention proposes a method in which a means for suppressing grain growth during firing is further added so that the method can be applied to fine-grained alumina.
また、本発明は、本発明の焼成温度に於いて転換し生成
識別される特定性状のアルミナ、例えば、活性アルミナ
・遷移アルミナ・α−アルミナなどの製造方法としても
汎用的に適用することが出来るものである。Furthermore, the present invention can be applied generally as a method for producing alumina with specific properties that are converted and produced at the firing temperature of the present invention, such as activated alumina, transition alumina, and α-alumina. It is something.
本発明の主目的は、粉体状及び微粒子状のアルミナを提
供することであるが、派生的に造粒状や成形体状の高純
度アルミナの製造法としても適用出来るものである。そ
の場合、焼成条件、例えば焼成時間の長短により、マト
リックス全体の高純度化と共に表面域のみの高純度化を
発現させることができる。Although the main purpose of the present invention is to provide alumina in the form of powder or fine particles, it can also be applied as a method for producing high-purity alumina in the form of granules or compacts. In that case, by changing the firing conditions, for example, the length of the firing time, it is possible to achieve high purity of the entire matrix as well as high purity of only the surface region.
（発明の構成）
本発明は、原料アルミナを除去対象不純物成分に応じて
０．５気圧以下の減圧雰囲気で８００℃以上の温度に焼
成することを特徴とする高純度アルミナの製造方法に関
するものである。(Structure of the Invention) The present invention relates to a method for producing high-purity alumina, which is characterized in that raw alumina is fired at a temperature of 800°C or higher in a reduced pressure atmosphere of 0.5 atm or lower depending on the impurity component to be removed. be.
更には、原料アルミナが平均粒子径が５μｍ以下の微粒
アルミナである場合に、事前に微粒原料アルミナを炭素
質物質で被覆した後、除去対象不純物成分に応じて０．
５気圧以下の減圧雰囲気で８゜０℃以上に焼成し、次い
で常圧の酸化性雰囲気で加熱し脱炭処理することを特徴
とする微粒高純度アルミナの製造方法に関するものであ
る。Furthermore, when the raw material alumina is fine-grained alumina with an average particle diameter of 5 μm or less, the fine-grained raw material alumina is coated with a carbonaceous material in advance, and then the fine-grained raw material alumina is coated with a carbonaceous material, and then the fine-grained raw material alumina is coated with a carbonaceous material in advance, and then 0.0000.
The present invention relates to a method for producing fine-grained high-purity alumina, which is characterized by firing at a temperature of 8° C. or higher in a reduced pressure atmosphere of 5 atm or less, and then heating and decarburizing in an oxidizing atmosphere at normal pressure.
ここで「原料アルミナ」なる言葉は、化学的に活性なγ
−アルミナとか遷移アルミナなどの中間アルミナや化学
的に安定なα−アルミナ等の酸化アルミニウムを意味す
る。従って、アルミナに至る以前の出発原料の形態は特
に問わず、例えば、バイヤープロセス法による水酸化ア
ルミニウム、ジブサイト、ダイアスポア、他の工程での
副生水酸化アルミニウムゲル、或いは塩化アルミニウム
・硫酸アルミニウム・アルミニウムみょうばん・有機ア
ルミニウム化合物などの熱分解してアルミナに転換し得
るアルミニウム化合物等をアルミナ源とすることが出来
、それらから製造されたアルミナが原料アルミナとして
使用される。従って、それらのアルミナ源に対する処理
工程に引き続いてまたは連続不可分的に、例えば昇温過
程において水酸化アルミニウムゲルからアルミナに転換
しつつ本発明の実施に移行することが出来る。Here, the term "raw material alumina" refers to chemically active γ
- Means intermediate aluminas such as alumina and transition alumina, and chemically stable aluminum oxides such as α-alumina. Therefore, the form of the starting material before producing alumina does not matter; for example, aluminum hydroxide produced by the Bayer process, gibbsite, diaspore, aluminum hydroxide gel produced as a by-product in other processes, or aluminum chloride, aluminum sulfate, or aluminum. Aluminum compounds that can be thermally decomposed and converted into alumina, such as alum and organic aluminum compounds, can be used as an alumina source, and alumina produced from them is used as the raw material alumina. Therefore, the practice of the present invention can be carried out subsequent to the treatment steps for these alumina sources, or continuously and inseparably, for example, with conversion of aluminum hydroxide gel to alumina in a heating process.
この場合、アルミナ源によって含有される金属酸化物不
純物成分とその含を量が異なることが想像されるが、バ
イヤープロセス法により得られるものはボーキサイト鉱
石をカセイソーダで処理して取得されるものであり、前
述したような種類以外の不純物が含有されることは少な
く、万一含有されていても実用上の問題を引き起す程の
含有量を呈することは少なく、本発明を適用するものと
してバイヤープロセス法を経て得られたアルミナが最適
である。In this case, the metal oxide impurity component and its content may differ depending on the alumina source, but the alumina obtained by the Bayer process method is obtained by treating bauxite ore with caustic soda. , impurities other than the types mentioned above are rarely contained, and even if they are contained, they are unlikely to be present in amounts that would cause practical problems. Alumina obtained through the process is most suitable.
更に、それらの原料アルミナの形状は、前記した様に、
本発明による焼成処理以前に粉砕や造粒操作などを施し
、粉体以外に微粒状、造粒状或いは成形体状に加工した
ものも適用できる。従って、原料アルミナの粒径は、特
に限定されるものではなく、例えば０．１μｍ〜５璽鳳
の広範囲のものが適用され、肉厚５鰭程度の板状体の製
造にも適用される。その場合、粒径の高純度化率への影
響は少なく、焼成時間は所望の高純度化レベル・処理量
炉処理能力等に応じて１０分〜１００時間とされる。
本発明は、この種の原料アルミナを焼成温度でアルミナ
に対して不活性な、例えばカーボン容器や黒鉛容器に収
納して密閉焼成炉内に入れ、０．５気圧以下の減圧雰囲
気で８００℃以上に焼成するが、所望の不純物成分レベ
ルに応じて焼成条件が設定される。Furthermore, the shape of the raw material alumina is, as mentioned above,
In addition to powder, those processed into fine granules, granules, or molded bodies by subjecting them to pulverization, granulation, etc. before the firing process according to the present invention can also be used. Therefore, the particle size of the raw material alumina is not particularly limited, and a wide range of particle sizes, for example from 0.1 μm to 5 μm, can be applied, and it can also be applied to the production of plate-like bodies with a wall thickness of about 5 μm. In that case, the influence of the particle size on the high purity rate is small, and the firing time is set to 10 minutes to 100 hours depending on the desired high purity level, throughput and furnace processing capacity.
In the present invention, raw material alumina of this type is stored in a container that is inert to alumina at a firing temperature, such as a carbon container or a graphite container, and placed in a closed firing furnace at a temperature of 800°C or higher in a reduced pressure atmosphere of 0.5 atmosphere or lower. The firing conditions are set depending on the desired level of impurity components.
即ち、用途や所望の特性レベルに応じて許容できる不純
物成分とその許容レベルが異なるので、それらの所定条
件に応じて減圧度・焼成温度・焼成時間を任意に選定し
うる。That is, since the permissible impurity components and their permissible levels differ depending on the use and desired property level, the degree of pressure reduction, firing temperature, and firing time can be arbitrarily selected according to these predetermined conditions.
現在、高品位アルミナとして低ソーダアルミナが多用さ
れていること、バイヤー法アルミナに含有されている不
純物として酸化ナトリウム（ソーダ）分が一番多量に含
有されていること等から高純度アルミナとして提供する
ためには、脱ソーダ化を図ることが最低条件となる。Currently, low-soda alumina is widely used as high-grade alumina, and Bayer process alumina contains the largest amount of sodium oxide (soda) as an impurity, so we provide it as high-purity alumina. To achieve this goal, the minimum requirement is to eliminate soda.
しかるに、最低限、脱ソーダ（ＮａｚＯ）化を図るには
、０．５気圧以下の減圧雰囲気下で８００℃以上に焼成
するのが望ましく、ソーダ含有量、除去目標レベル或い
は炉処理能力との兼合いにより１０分〜１００時間の焼
成時間とされる。この場合、０．５気圧以上又は８００
℃以下であると、ソーダ分の除去効率が低（実用的でな
く、減圧度と焼成温度を高くする程焼成時間を短縮化で
きる。実用的には、０．５気圧〜０．１）−ルの減圧雰
囲気下で８００〜１６００℃の焼成温度とするのが好ま
しく、１７００℃以上になるとアルミナロスも無視出来
なくなるので好ましくない。However, in order to remove soda (NazO) at the very least, it is desirable to perform firing at a temperature of 800°C or higher in a reduced pressure atmosphere of 0.5 atm or lower, depending on the soda content, removal target level, or furnace processing capacity. Depending on the condition, the firing time is 10 minutes to 100 hours. In this case, 0.5 atm or more or 800 atm
If the temperature is below ℃, the removal efficiency of the soda component is low (not practical; the firing time can be shortened by increasing the degree of vacuum and firing temperature.Practically speaking, from 0.5 atm to 0.1). It is preferable to set the firing temperature to 800 to 1,600°C under a reduced pressure atmosphere in a vacuum chamber, and temperatures higher than 1,700°C are not preferable because alumina loss cannot be ignored.
一方、現実には数種類の不純物が共存し、それらを同時
に除去することが課題となるが、本発明を適用する場合
、酸化ナトリウム（ＮａｚＯ） ＞酸化鉄（ＦｅｚＯａ
） 〉酸化けい素（Ｓｉｎｇ） ＞酸化マグネシウム（
ＭｇＯ） ＞酸化カルシウム（Ｃａｂ）の順の除去難易
度であり、酸化ナトリウムが一番容易に除去可能である
。On the other hand, in reality, several types of impurities coexist, and it is a challenge to remove them at the same time. However, when applying the present invention, sodium oxide (NazO) > iron oxide (FezOa
) 〉Silicon oxide (Sing) ＞Magnesium oxide (
The difficulty of removal is in the order of MgO)>calcium oxide (Cab), with sodium oxide being the easiest to remove.
各不純物成分に応じた減圧度と焼成温度条件は次の通り
である。The degree of pressure reduction and firing temperature conditions according to each impurity component are as follows.
なお、これらの減圧度と焼成温度とをいずれも満足しな
い条件下では各成分の除去効率が低く実用的でなく、焼
成処理時間は、所望の不純物除去レベル等に応じて１０
分から１００時間の範囲で適宜選定される。Note that under conditions where neither the degree of pressure reduction nor the firing temperature is satisfied, the removal efficiency of each component is low and it is not practical, and the firing treatment time may vary depending on the desired level of impurity removal, etc.
The time period is appropriately selected within the range of minutes to 100 hours.
その場合、減圧度と焼成温度を高めることによって除去
効率を向上させることが出来、焼成時間も短縮される。In that case, the removal efficiency can be improved by increasing the degree of vacuum and the firing temperature, and the firing time can also be shortened.
これは、平均粒径１５μｍで酸化鉄（ＦｅｚＯ：＋）を
２５０ＰＰＭ含有する中間アルミナを用い焼成時間を１
時間としたときの減圧度・焼成温度の変化による酸化鉄
Ｐｅ、Ｏ，除去率への影響を示す第１図に例示されると
ころから示唆される。This uses intermediate alumina with an average particle size of 15 μm and containing 250 PPM of iron oxide (FezO:+), and the firing time is 1.
This is suggested by the example shown in FIG. 1, which shows the influence of changes in the degree of reduced pressure and firing temperature on the removal rate of iron oxides, Pe and O, over time.
又、除去目標不純物の中で最も除去困難な成分に応じた
減圧度と焼成温度の条件下で焼成処理することにより、
所望の複数の不純物を同時に除去することが出来る。In addition, by performing calcination treatment under conditions of reduced pressure and calcination temperature that correspond to the component that is most difficult to remove among the target impurities,
A plurality of desired impurities can be removed simultaneously.
なお、上記範囲内において更に好ましい減圧度と焼成温
度条件を挙げれば、次の通りである。Further, more preferable pressure reduction degree and firing temperature conditions within the above range are as follows.
これら減圧度と焼成温度条件の上限は、使用設備の真空
減圧機の能力や焼成炉の炉壁材の耐火度に応じて決定さ
れるものであり、通常は、０．１ト一ル程度の減圧度と
１６００℃程度の焼成温度までが実用的である。又、こ
のような減圧度と焼成温度に於いて原料アルミナを処理
するものであるので、使用する焼成炉の炉壁材からの汚
染も考えられるため、炉壁材を焼成処理中に不純物が揮
散させることのない程度の純度のものを用いて築炉する
ことが望ましい。The upper limits of these pressure reduction degrees and firing temperature conditions are determined according to the capacity of the vacuum reducer of the equipment used and the fire resistance of the furnace wall material of the firing furnace, and are usually around 0.1 torr. A degree of reduced pressure and a firing temperature of up to about 1600° C. are practical. In addition, since raw alumina is processed at such reduced pressure and firing temperature, there is a possibility of contamination from the furnace wall material of the furnace used, so impurities may volatilize from the furnace wall material during the firing process. It is desirable to construct a furnace using a material of such purity that it will not cause any damage.
従って、例えばシリカ−アルミナ系断熱材を用いた炉の
ようなものは不適であり、高純度アルミナ質断熱材や高
純度黒鉛質断熱材を用いて築炉した雰囲気制御炉が好適
であり、減圧雰囲気は水封ポンプや真空ポンプを焼成炉
に連接することにより形成される。Therefore, for example, furnaces using silica-alumina insulation are not suitable, and atmosphere-controlled furnaces constructed using high-purity alumina insulation or high-purity graphite insulation are suitable. The atmosphere is created by connecting a water ring pump or a vacuum pump to the firing furnace.
その際、焼成炉内で気化した不純物が系外に排出された
後、低温域に触れると再凝縮し固体化するので、焼成炉
と真空減圧機との間に凝縮器を設けて、気化した不純物
をトラップすることが望ましい。それと同時に、装置点
検時に、炉壁の低温部や配管等に沈着した凝縮不純物を
清掃除去する作業を行なうことが適切である。At that time, after the impurities vaporized in the firing furnace are discharged outside the system, they re-condense and solidify when they touch the low temperature range, so a condenser is installed between the firing furnace and the vacuum decompressor to prevent the vaporization. It is desirable to trap impurities. At the same time, it is appropriate to clean and remove condensed impurities deposited on the low-temperature parts of the furnace wall, piping, etc. when inspecting the equipment.
本発明は更に、原料アルミナが５μｍ以下、より好まし
くは１μｍ以下の微粒子より成る場合に、粒子成長を抑
えつつ高純度化を達成する手段を提案するものであるが
、具体的には平均粒子径が５μｍ以下の微粒原料アルミ
ナを炭素質物質で被覆した後、除去対象不純物成分に応
じて０．５気圧以下の減圧雰囲気で８００℃以上に焼成
し、次いで常圧の酸化性雰囲気、例えば空気中で加熱し
脱炭処理する方法を提案するものである。The present invention further proposes a means for achieving high purity while suppressing particle growth when raw material alumina consists of fine particles of 5 μm or less, more preferably 1 μm or less. After coating fine raw material alumina with a particle size of 5 μm or less with a carbonaceous material, it is fired at a temperature of 800°C or higher in a reduced pressure atmosphere of 0.5 atm or less depending on the impurity component to be removed, and then heated in an oxidizing atmosphere at normal pressure, such as in air. This paper proposes a method for decarburizing by heating.
即ち、前述のプロセスに加えて焼成処理前に微粒原料ア
ルミナの個々の粒子を炭素質物質で被覆することにより
相互に分離しく焼成処理時に粒子間の固体拡散が発生す
ることを阻止するものである）、焼成処理後は、酸化性
雰囲気で加熱することにより炭素質物質を燃焼除去させ
アルミナ表面から脱炭処理することから成る手段を付加
することによって、微粒原料アルミナから微粒高純度ア
ルミナを製造することを可能とするものである。That is, in addition to the above-mentioned process, each particle of the fine raw material alumina is coated with a carbonaceous material before the calcination treatment to separate them from each other and prevent solid diffusion between the particles from occurring during the calcination treatment. ), after the calcination treatment, by adding a means consisting of heating in an oxidizing atmosphere to burn off carbonaceous substances and decarburizing the alumina surface, fine grained high purity alumina is produced from fine grained raw material alumina. This is what makes it possible.
ここで、「炭素質物質」としては、原料アルミナの粒子
を被覆可能であり、焼成処理に続く酸化性雰囲気下での
加熱によって燃焼除去し得るものであれば、いずれの炭
素質物質も使用することが出来る。Here, as the "carbonaceous material", any carbonaceous material can be used as long as it can coat the raw material alumina particles and can be burned and removed by heating in an oxidizing atmosphere following the calcination treatment. I can do it.
代表例としては、カーボンブラック、グラファイト粉末
、活性炭粉末、コークス粉末などの炭素粉末を挙げるこ
とが出来る。その他に、焼成温度以下で炭素若しくは炭
素系物質に変換され、昇温過程又は焼成処理中に炭素若
しくは炭素系物質に変換した状態で粒子の被覆状態を保
持でき、その後の空気などの酸化性雰囲気中での加熱燃
焼によって除去可能な、液体若しくは固体の炭素系化合
物も使用することが出来る。このような炭素系化合物の
具体例としては、木材粉末、でんぷん、ショ糖、天然若
しくは合成高分子、例えば結晶性セルロース、ポリエチ
レン、ポリビニルブチラール、スチレン樹脂、フェノー
ル樹脂、ポリ塩化ビニリチン、ポリフェニレン、ポリビ
ニルアルコール、ポリエチレングリコール等を挙げるこ
とができる。Typical examples include carbon powders such as carbon black, graphite powder, activated carbon powder, and coke powder. In addition, it is possible to convert into carbon or carbon-based substances below the firing temperature, maintain the coated state of the particles in the state of being converted to carbon or carbon-based substances during the heating process or firing process, and then use the oxidizing atmosphere such as air. It is also possible to use liquid or solid carbon-based compounds that can be removed by heating and combustion in the reactor. Specific examples of such carbon-based compounds include wood powder, starch, sucrose, natural or synthetic polymers such as crystalline cellulose, polyethylene, polyvinyl butyral, styrene resin, phenolic resin, polyvinyritine chloride, polyphenylene, and polyvinyl alcohol. , polyethylene glycol, and the like.
これらは、いずれも高純度アルミナ化時の所望の不純物
レベルに対応して、それ以上の純度のものが使用される
が、その条件を満足すれば、タール・ピッチなどの重質
炭化水素も使用できる。All of these are used with higher purity depending on the desired impurity level when producing high-purity alumina, but heavy hydrocarbons such as tar and pitch can also be used if the conditions are met. can.
しかるに、特に汎用性を考慮すれば、カーボンブラック
、固体又は液体状のフェノール樹脂が好ましい。これら
の炭素質物質は単独でも組合せても使用することが出来
る。又、炭素系化合物並びにその液状体を使用する場合
には、８００℃近傍までの昇温過程を常圧下で行なうこ
とにより、脱気やそれらの炭素系化合物の炭化を図りな
がら昇温させることが出来る。なお、メタノールやエタ
ノールなどの揮発性存機化合物は炭化残留物を残すこと
なく焼成温度では消失してしまうので使用することは出
来ない。However, especially considering versatility, carbon black and solid or liquid phenol resin are preferred. These carbonaceous materials can be used alone or in combination. Furthermore, when carbon-based compounds and their liquids are used, the temperature can be increased to around 800°C under normal pressure, thereby degassing and carbonizing the carbon-based compounds. I can do it. Note that volatile organic compounds such as methanol and ethanol cannot be used because they disappear at the calcination temperature without leaving any carbonized residue.
炭素質物質による原料アルミナの被覆方法は、特に限定
されるものでははなく、適宜の方法で実施することが出
来る。例えば、（１）原料アルミナを固体または液体状
の炭素質物質と混合機を使用して混合・被覆する方法、
（２）液体状炭素質物質を有機溶媒中に分散させた後、
それを原料アルミナに噴霧し被覆する方法、（３）原料
アルミナをカーボンブラック等と共に粉砕機に入れ粉砕
と被覆を同時に行なう方法等を適用することが出来る。The method of coating the raw material alumina with the carbonaceous material is not particularly limited, and any suitable method can be used. For example, (1) a method of mixing and coating raw material alumina with a solid or liquid carbonaceous material using a mixer;
(2) After dispersing the liquid carbonaceous material in an organic solvent,
A method of spraying the raw material alumina and coating it thereon, and (3) a method of putting the raw material alumina together with carbon black etc. in a pulverizer and performing pulverization and coating at the same time, etc. can be applied.
また、便法として、前工程に当たる水酸化アルミニウム
の段階で炭素質物質で被覆した後に脱水加熱して炭素質
物質で被覆されたアルミナ状のものとする過程も採用し
得るものである。Furthermore, as an expedient method, it is possible to adopt a process in which aluminum hydroxide is coated with a carbonaceous material in the previous step, and then dehydrated and heated to form an alumina-like product coated with a carbonaceous material.
また、カーボンブラックなどの固体炭素質物質を使用す
る場合には、炭素質物質の粒子径は、原料アルミナ粒子
の粒子径の１／１０以下程度が好ましく、例えば１０人
〜１μｍの範囲のものが実用的である。In addition, when using a solid carbonaceous material such as carbon black, the particle size of the carbonaceous material is preferably about 1/10 or less of the particle size of the raw material alumina particles, for example, in the range of 10 μm to 1 μm. It's practical.
炭素質物質の使用量は、原料アルミナ粉体を被覆できる
量程度で十分であるが、原料アルミナ１００重量部に対
して１〜１００重量部、好ましくは５〜２０重量部であ
る。１００重量部を超えても、粒子成長阻止効果の向上
は認められず、むしろ燃焼除去量がむやみに増加して不
経済である。The amount of carbonaceous material to be used is sufficient to cover the raw alumina powder, and is 1 to 100 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of raw alumina. Even if the amount exceeds 100 parts by weight, no improvement in the particle growth inhibiting effect is observed, and rather the amount removed by combustion increases unnecessarily, which is uneconomical.
炭素質物質で被覆した原料アルミナは、次いで前述した
と同一条件で減圧雰囲気下での焼成処理を行ない、更に
所望により篩分は出来る炭素質粉末を除去する工程を経
て脱炭処理を行なう。The raw material alumina coated with a carbonaceous material is then subjected to a calcination treatment under a reduced pressure atmosphere under the same conditions as described above, and is further decarburized through a step of removing carbonaceous powder that can be sieved if desired.
即ち、生成した高純度アルミナを空気雰囲気などの酸化
性雰囲気の常圧下で６００〜１０００℃で１０分、〜
１０時間加熱し、炭素質物質を燃焼・除去させる。この
場合、更に好ましくは６５０〜８５０℃で３０分〜３時
間の加熱処理とすることができる。That is, the produced high-purity alumina is heated at 600 to 1000°C for 10 minutes in an oxidizing atmosphere such as air under normal pressure.
Heat for 10 hours to burn and remove carbonaceous substances. In this case, the heat treatment can be more preferably carried out at 650 to 850°C for 30 minutes to 3 hours.
上記のように焼成処理して得られた高純度アルミナは、
時として一次粒子が凝集した状態の凝集粒子として得ら
れることがあるので、後工程として解砕処理を施して単
粒子に分離することが出来る。この解砕処理は、ボール
ミル、シェフ）ミル、振動ミル、混合撹拌型粉砕機など
を用いて２０分〜１０時間程度処理することによって行
なわれる。The high-purity alumina obtained by the calcination treatment as described above is
Since primary particles are sometimes obtained as agglomerated particles, they can be separated into single particles by disintegration treatment as a post-process. This crushing treatment is carried out for about 20 minutes to 10 hours using a ball mill, a chef's mill, a vibration mill, a mixing agitation type crusher, or the like.
本発明で得られる高純度アルミナは、単独で各種製品の
焼結原料とされたり、他の原料と混合して用いる添加剤
として用いられる。The high-purity alumina obtained by the present invention can be used alone as a sintering raw material for various products, or as an additive mixed with other raw materials.
例えば、点火栓碍子・ＩＣ基板・切削工具・研摩材・セ
ラミックスフィルタ・透光性セラミックス等の焼結原料
とか、人造宝石・医薬品・触媒等の他の材料への添加剤
、或いは高純度アルミニウム化合物の製造原料などに適
用される。For example, sintering raw materials for spark plug insulators, IC boards, cutting tools, abrasives, ceramic filters, translucent ceramics, etc., additives for other materials such as artificial jewelry, medicines, catalysts, etc., or high-purity aluminum compounds. Applicable to manufacturing raw materials, etc.
（発明の作用）
本発明は、第一に減圧雰囲気下で焼成処理することを特
徴とするものであるが、これは除去対象不純物の高温度
下に於ける熱解離反応を利用し、反応系を減圧下とする
ことによって熱解離を促進することが出来るものと推考
される。(Function of the Invention) The present invention is first characterized by performing a calcination treatment under a reduced pressure atmosphere, which utilizes a thermal dissociation reaction of impurities to be removed at high temperatures, and the reaction system It is presumed that thermal dissociation can be promoted by reducing the pressure.
更に、本発明は、第二に、微粒原料アルミナに対して炭
素質物質による被覆をした後、減圧雰囲気下での焼成処
理を行なうことを特徴とするものである。Furthermore, the second feature of the present invention is that after the fine grain raw material alumina is coated with a carbonaceous material, a firing treatment is performed in a reduced pressure atmosphere.
通常、微粒原料アルミナ粒子相互に表面接触している状
態で１０００℃以上に加熱されると、隣接している粒子
間での固体拡散が顕著になり粒子成長が発生し、粗粒子
化が発生してしまう。そこで、本発明は、後工程で燃焼
除去可能な炭素質物質で原料アルミナ粒子を被覆して単
粒子状に存在させた状態で焼成することによって、原料
アルミナ粒子の相互接触を阻止しつつ焼成処理を行ない
、その後燃焼除去させることによって微粒高純度アルミ
ナ得ることを可能とするものである。Normally, when fine raw material alumina particles are heated to 1000°C or higher while their surfaces are in contact with each other, solid diffusion between adjacent particles becomes noticeable, particle growth occurs, and coarse particles occur. It ends up. Therefore, the present invention provides a method for firing raw alumina particles while preventing mutual contact between the raw alumina particles by coating the raw alumina particles with a carbonaceous material that can be removed by combustion in a subsequent process and firing the raw alumina particles in the form of single particles. It is possible to obtain fine particles of high purity alumina by carrying out this process and then removing it by combustion.
上述の手段を採用することにより、アルミナ中の不純物
は、Ｎａｚｏ ２ ＰＰＭ、 ＦｅｚＯ２ＰＰＭ。By employing the above-mentioned means, the impurities in alumina are reduced to Nazo 2 PPM and FezO 2 PPM.
５ｉＯｚ ２ ＰＰＭ、 ＭｇＯ１０ＰＰＭ、 Ｃａ
０１０ＰＰＭのレベルまで低下させることが出来ると共
に、粒子成長を従来の１／４〜１１５程度に止めること
が出来る。又、この場合、原料アルミナ粒子が単粒子状
に存在する状態で加熱されるため、個々の粒子の球状化
が二次的に起こり原料粒子よりも真球度の高いアルミナ
を生成させることが出来る。5iOz 2 PPM, MgO10PPM, Ca
It is possible to reduce the particle growth to a level of 0.010 PPM, and also to stop the particle growth to about 1/4 to 115 of the conventional level. In addition, in this case, since the raw material alumina particles are heated in a state in which they exist in the form of single particles, the spheroidization of the individual particles occurs secondarily, making it possible to produce alumina with higher sphericity than the raw material particles. .
（実施例） 以下、実施例を挙げて本発明を更に具体的に説明する。(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.
なお、組成分析は、原子吸光分析計、蛍光Ｘ線分析計に
より、平均粒径の測定は、セディグラフ法によって行な
った。The composition analysis was performed using an atomic absorption spectrometer and a fluorescent X-ray spectrometer, and the average particle diameter was measured using the Sedigraph method.
〔実施例１〕
バイヤープロセス法で製造された水酸化アルミニウム（
日本軽金属■製部品名ｒＢ３０３Ｊで平均粒径３０μｍ
）を電気炉で８００℃で１時間加熱して脱水させγ−ア
ルミナとした。[Example 1] Aluminum hydroxide produced by Bayer process method (
Part name: rB303J manufactured by Nippon Light Metal ■ Average grain size: 30 μm
) was heated in an electric furnace at 800° C. for 1 hour to dehydrate it and obtain γ-alumina.
このγ−アルミナを１０ｃｍ深さで黒鉛製容器に入れ、
黒鉛質断熱成形体で築炉した焼成炉中の複数段の棚上に
設置し、次いで炉内を真空ポンプで減圧しつつ、加熱電
源を入れ、３０トールの減圧度で１０００℃２時間の焼
成処理を行なった。焼成終了後は、炉内に窒素ガスを導
入しつつ室温まで冷却した。なお、黒鉛製容器及び黒鉛
炉は、９９゜９％以上の純度の黒鉛材から製作されたも
のである。This γ-alumina was placed in a graphite container at a depth of 10 cm.
It was installed on multiple shelves in a firing furnace made of graphite heat-insulating molded bodies, and then the heating power was turned on while reducing the pressure inside the furnace with a vacuum pump, and firing was performed at 1000°C for 2 hours at a reduced pressure of 30 torr. Processed. After the firing was completed, the furnace was cooled to room temperature while nitrogen gas was introduced into the furnace. The graphite container and graphite furnace are manufactured from graphite material with a purity of 99.9% or higher.
このような処理により、当初ソーダ（Ｎａ２０）分とし
て２１００ＰＰＭ含有していたものから、ソーダ分が５
０ＰＰＭの低ソーダアルミナを得ることが出来た。Through this treatment, the soda content was reduced from 2100 PPM as soda (Na20) content to 5.
0PPM low soda alumina could be obtained.
なお、比較例として、同じγ−アルミナを、シリカ−ア
ルミナ系断熱レンガ（Ａｌｔ０３６０％。As a comparative example, the same γ-alumina was used in a silica-alumina insulation brick (Alt0360%).
５ｉＯｚ３５％、 Ｆｅ２Ｏ３２％、ＴｉＯ２２％、
Ｍｇ００．５％ＣａＯ０，５％から成る）を炉壁材とし
たシリコニット型電気炉で、常圧の空気雰囲気下で１０
００℃２時間焼成処理した。これにより得たアルミナ中
のソーダ分を測定したところ、３０００ＰＰＭで脱ソー
ダ効果は見られなかった。5iOz35%, Fe2O32%, TiO22%,
A siliconite electric furnace with furnace wall material consisting of 0.5% Mg0.5% CaO0.5%,
Firing treatment was performed at 00°C for 2 hours. When the soda content in the alumina thus obtained was measured, it was 3000 PPM and no soda removal effect was observed.
なお、本実施例と比較例で使用した黒鉛製容器・黒鉛炉
・シリコニット型電気炉を同様に使用して以下の実施例
と比較例を行なった。Note that the following Examples and Comparative Examples were conducted using the same graphite containers, graphite furnaces, and siliconite electric furnaces used in the Examples and Comparative Examples.
〔実施例２〕
平均粒径０．６μｍの低ソーダアルミナ（口軽化工■製
商品名ｒＬｓ２３Ｊ ：α−アルミナ）を黒鉛製容器に
入れ、黒鉛炉で、２０トールの減圧下で１２００℃２時
間の焼成処理を行なった。[Example 2] Low soda alumina (trade name: rLs23J: α-alumina, manufactured by Kuchirai Kako ■) with an average particle size of 0.6 μm was placed in a graphite container and heated at 1200°C under a reduced pressure of 20 Torr for 2 hours in a graphite furnace. A firing process was performed.
原料低ソーダアルミナは、ソーダ（ＮａｚＯ）分として
５５０ＰＰＭであったが、上記処理したアルミナ中のソ
ーダ分はＩＯＰＰＭであった。The raw material low soda alumina had a soda (NazO) content of 550 PPM, but the soda content in the above-treated alumina was IOPPM.
〔実施例３〕
平均粒径１５μｍの水酸化アルミニウム（日本軽金属■
裂開品名ｒＢ１５３Ｊ）を６００℃で２時間加熱しγ−
アルミナとした。この中間アルミナをカーボン容器（純
度は黒鉛製容器と同じ。）に収納し、黒鉛炉で３トール
下で１２００℃３時間の焼成処理を行なった。[Example 3] Aluminum hydroxide with an average particle size of 15 μm (Nippon Light Metal ■
γ-
Made of alumina. This intermediate alumina was placed in a carbon container (purity is the same as the graphite container), and fired in a graphite furnace at 1200° C. for 3 hours under 3 Torr.
なお、比較例１として同時に先きに得た中間アルミナを
実施例１と同一のシリコニット型電気炉で、常圧の空気
中で１２００℃３時間の加熱処理を行なった。これらに
より得られた結果は次の通りであった。As Comparative Example 1, the previously obtained intermediate alumina was also heat-treated at 1200° C. for 3 hours in air at normal pressure in the same siliconite electric furnace as in Example 1. The results obtained were as follows.
〔実施例４・５・６〕
バイヤープロセス法で製造された水酸化アルミニウム（
日本軽金属■裂開品名ｒＢ１４０３Ｊを６００℃で加熱
処理して平均粒径０．２μｍのγ−アルミナを得た。[Examples 4, 5, 6] Aluminum hydroxide produced by Bayer process method (
Nippon Light Metal ■Cracked product name: rB1403J was heat treated at 600°C to obtain γ-alumina with an average particle size of 0.2 μm.
この中間アルミナを黒鉛容器に入れ黒鉛炉にセントし、
以下の３水準の条件下で焼成処理を行なった。This intermediate alumina is placed in a graphite container and sent to a graphite furnace.
Firing treatment was performed under the following three conditions.
（以下余白）
焼成後の生成アルミナは、Ｘ線回折測定の結果、α−ア
ルミナとなっており、焼成前後での不純物濃度等の変化
は次の通りであった。(The following is a blank space) The alumina produced after firing was found to be α-alumina as a result of X-ray diffraction measurement, and the changes in impurity concentration etc. before and after firing were as follows.
又同時に、比較例２として中間アルミナをシリコニット
炉で、１５００℃２時間の焼成処理を行なったので、同
様に示す。At the same time, as Comparative Example 2, intermediate alumina was fired in a siliconite furnace at 1500° C. for 2 hours, and the results are similarly shown.
これらから、減圧度と焼成温度を調整することにより高
純度化率が変わり、焼成温度の上昇と共に粗粒化が進む
ことが分かる。From these results, it can be seen that the degree of purification changes by adjusting the degree of reduced pressure and the firing temperature, and that grain coarsening progresses as the firing temperature increases.
〔実施例７〕
塩化アルミニウム六水和物を電気炉で８００℃で２時間
加熱し、中間アルミナとした。[Example 7] Aluminum chloride hexahydrate was heated at 800° C. for 2 hours in an electric furnace to obtain intermediate alumina.
この中間アルミナを黒鉛炉で１トールの減圧下で１４５
０℃２時間焼成処理した。得られたα−アルミナの不純
物量は次の通りであった。This intermediate alumina was heated in a graphite furnace under a reduced pressure of 145
Firing treatment was performed at 0°C for 2 hours. The amount of impurities in the obtained α-alumina was as follows.
〔実施例８・９・１０〕
実施例４で得た０、２μｍの中間アルミナ１０ｋｇとカ
ーボンブランク（新日鉄化学■製商品名「ニテロン＃２
００Ｊ）１ｋｇの割合で混合し、アルミナ製ボールを使
用したボールミル中で２時間部合被覆した。[Examples 8, 9, 10] 10 kg of intermediate alumina of 0 and 2 μm obtained in Example 4 and a carbon blank (trade name "Niteron #2" manufactured by Nippon Steel Chemical Co., Ltd.)
00J) were mixed at a ratio of 1 kg and partially coated for 2 hours in a ball mill using alumina balls.
次いで、カーボンブラックで被覆された中間アルミナを
３ ｃｍ深さで黒鉛容器に入れ、黒鉛炉中で、３水準の
焼成処理を行なった。The intermediate alumina coated with carbon black was then placed in a graphite container at a depth of 3 cm and subjected to three levels of calcination treatment in a graphite furnace.
焼成後、炉内にアルゴンガスを導入し室温まで冷却した
。得られたα−アルミナをアルミナ製トレーに移し、通
常の空気雰囲気の電気炉内に設置し、空気を１ｒｒｒ／
ｈｒの流量で流しながら８００℃で２時間処理し、カー
ボンブランクを燃焼除去させた。After firing, argon gas was introduced into the furnace and the furnace was cooled to room temperature. The obtained α-alumina was transferred to an alumina tray, placed in an electric furnace with a normal air atmosphere, and the air was
The carbon blank was burned and removed by treatment at 800° C. for 2 hours while flowing at a flow rate of hr.
生成アルミナの特性は、次の通りであったが、実施例４
〜６と対比するとき粗粒子化が適切に抑制されつつ高純
度化が果たされていることが分かる。また、実施例１０
で、更に解砕処理をしたところ１．１μｍのアルミナが
得られた。The properties of the produced alumina were as follows. Example 4
When compared with No. 6 to No. 6, it can be seen that high purity was achieved while coarse particle formation was appropriately suppressed. Also, Example 10
When the material was further crushed, alumina of 1.1 μm was obtained.
〔実施例１１〕 γ−アルミナ（Ｎａｚｏ ３６００ＰＰＭ。[Example 11] γ-Alumina (Nazo 3600PPM.
Ｆｅｔ（ｈ ２３０ＰＰＭ 、 ５ｉＯｚ ２４０
ＰＰＭ 。Fet (h 230PPM, 5iOz 240
PPM.
ＭｇＯ２００ＰＰＭ 、 Ｃａ０７５ＰＰＭ ）を黒鉛
製容器に入れ黒鉛炉内にセットした後、１０００℃まで
常圧で昇温させ、その後減圧と昇温を進め、２トール・
１６００℃で２時間焼成処理したところ、不純物として
はＮａｔｏ ２ＰＰＭ 、 ＦｅｚＯ＊ ２ＰＰ
Ｍ 。After putting MgO200PPM, Ca075PPM) into a graphite container and setting it in a graphite furnace, the temperature was raised to 1000℃ at normal pressure, and then the pressure was reduced and the temperature was increased to 2 Torr.
When calcined at 1600°C for 2 hours, impurities such as Nato 2PPM and FezO* 2PP were found.
M.
Ｓｉｎｇ ２ＰＰＭ 、 ＭｇＯ５ＰＰＭ 、 Ｃ
ａＯ８ＰＰＭである高純度アルミナを得た。Sing 2PPM, MgO5PPM, C
High purity alumina of aO8PPM was obtained.
（発明の効果）
本発明は、不純物を含む原料アルミナを減圧下の高温焼
成処理する手段、並びに微粒原料アルミナを処理したい
場合にその微粒原料アルミナを炭素質物質で被覆した後
に減圧下の高温焼成処理を行なう手段等を提案するもの
であり、
■ 減圧度、焼成温度、焼成時間等の条件を調整するこ
とにより、任意の高純度化率を容易に達成・変更するこ
とが出来る。(Effects of the Invention) The present invention provides a means for performing high-temperature firing treatment under reduced pressure on raw material alumina containing impurities, and when it is desired to treat fine-grained raw material alumina, the fine-grained raw material alumina is coated with a carbonaceous material and then subjected to high-temperature firing treatment under reduced pressure. This paper proposes a means for carrying out the treatment, etc.; (1) By adjusting conditions such as the degree of reduced pressure, calcination temperature, and calcination time, it is possible to easily achieve or change an arbitrary high purity rate.
従って、本発明は、製造方法と共に、精製方法、濃度調
整方法とも表現されるものであり、アルミナ中の不純物
を、ＮａｚＯ２ＰＰＭ。Therefore, the present invention can be expressed as a manufacturing method, a purification method, and a concentration adjustment method, in which impurities in alumina are removed from NazO2PPM.
ＦｅｚＯ２ＰＰＭ、 ５ｉｎ２２ ＰＰＭ、 Ｍｇ０
１０ＰＰＭ、 ＣａＯ１０ＰＰＭのレベルまで低下させ
ることが出来る。FezO2PPM, 5in22PPM, Mg0
It can be lowered to the level of 10PPM and CaO10PPM.
■ 同時に複数の不純物を除去できる単純なプロセスな
ので、低コストで高純度アルミナを提供することができ
る。■ Since it is a simple process that can remove multiple impurities at the same time, it is possible to provide high-purity alumina at low cost.
■ 安価なバイヤープロセス法によるアルミナを原料と
して、高純度アルミナを得ることが出来る。■ High-purity alumina can be obtained using inexpensive alumina produced by the Bayer process as a raw material.
■ 高温焼成処理にも拘わらず、粗粒化を抑えて高純度
で微粒なアルミナが容易に得られ、しかも球状度の高い
微粒アルミナを容易に得ることが出来る。(2) Despite the high-temperature firing process, it is possible to easily obtain fine-grained alumina with high purity by suppressing coarsening, and moreover, it is possible to easily obtain fine-grained alumina with high sphericity.
■ 中間アルミナを用いる場合には、α−アルミナ化処
理と高純化処理とを同時に達成できる。■ When intermediate alumina is used, α-alumina treatment and high purification treatment can be achieved at the same time.
等のメリットが発現される。Benefits such as these will be realized.
第１図は、本発明による中間アルミナの処理例であって
、焼成アルミナ中の酸化鉄分＜ｐｅｚｏｓ ）の除去効
率に対する減圧度と焼成温度との影ツを示す線図である
。
特許出願人 日本軽金属株式会社
株式会社 日軽技研FIG. 1 is a diagram illustrating an example of the treatment of intermediate alumina according to the present invention, showing the effect of the degree of reduced pressure and the firing temperature on the removal efficiency of iron oxide <pezos in fired alumina. Patent applicant Nippon Light Metal Co., Ltd. Nikkei Giken Co., Ltd.
Claims (3)
５気圧以下の減圧雰囲気で８００℃以上に焼成すること
を特徴とする高純度アルミナの製造方法。(1) The raw material alumina is 0.0% depending on the impurity component to be removed.
A method for producing high-purity alumina, characterized by firing at a temperature of 800°C or higher in a reduced pressure atmosphere of 5 atmospheres or lower.
素質物質で被覆した後、除去対象不純物成分に応じて０
．５気圧以下の減圧雰囲気で８００℃以上に焼成し、次
いで常圧の酸化性雰囲気で加熱し脱炭処理することを特
徴とする微粒高純度アルミナの製造方法。(2) After coating fine raw material alumina with an average particle size of 5 μm or less with a carbonaceous material, the
．． A method for producing fine-grained high-purity alumina, which comprises firing at a temperature of 800° C. or higher in a reduced pressure atmosphere of 5 atm or less, and then heating and decarburizing in an oxidizing atmosphere at normal pressure.
酸化けい素・酸化マグネシウム・酸化カルシウムのいず
れか一種又は二種以上であるときに、焼成条件が、その
中で一番除去されにくい成分に応じて下記に規定する焼
成条件に対応したものとすることを特徴とする請求項第
１項又は第２項に記載の高純度アルミナの製造方法。(3) The impurity components to be removed are sodium oxide, iron oxide,
When one or more of silicon oxide, magnesium oxide, and calcium oxide are used, the firing conditions shall correspond to the firing conditions specified below depending on the component that is the most difficult to remove. The method for producing high-purity alumina according to claim 1 or 2, characterized in that:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12565388A JPH0637293B2 (en) | 1988-05-25 | 1988-05-25 | Method for producing high-purity alumina |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12565388A JPH0637293B2 (en) | 1988-05-25 | 1988-05-25 | Method for producing high-purity alumina |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01298018A true JPH01298018A (en) | 1989-12-01 |
| JPH0637293B2 JPH0637293B2 (en) | 1994-05-18 |
Family
ID=14915337
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12565388A Expired - Fee Related JPH0637293B2 (en) | 1988-05-25 | 1988-05-25 | Method for producing high-purity alumina |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0637293B2 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04324037A (en) * | 1990-12-25 | 1992-11-13 | Sharp Corp | Turn table drive roller for microwave oven |
| JP2000160434A (en) * | 1998-11-24 | 2000-06-13 | Toshiba Monofrax Co Ltd | High purity alumina filament and its fiber product and fire-resistant insulating material |
| CN1330575C (en) * | 2005-07-27 | 2007-08-08 | 太原刚玉特种耐火材料有限公司 | Decarbonization method for producing alumina base high purity corundum |
| WO2008072501A1 (en) * | 2006-12-15 | 2008-06-19 | Nippon Light Metal Company, Ltd. | PROCESS FOR PRODUCING HIGH-PURITY α-ALUMINA |
| JP2009235181A (en) * | 2008-03-26 | 2009-10-15 | Hitachi Metals Ltd | Method for manufacturing fluorescent material |
| CN112851309A (en) * | 2021-01-26 | 2021-05-28 | 江苏新时高温材料股份有限公司 | High-thermal-shock low-creep corundum processing technology |
| WO2023073842A1 (en) * | 2021-10-27 | 2023-05-04 | 日本軽金属株式会社 | High-purity microparticle alumina powder |
-
1988
- 1988-05-25 JP JP12565388A patent/JPH0637293B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04324037A (en) * | 1990-12-25 | 1992-11-13 | Sharp Corp | Turn table drive roller for microwave oven |
| JP2000160434A (en) * | 1998-11-24 | 2000-06-13 | Toshiba Monofrax Co Ltd | High purity alumina filament and its fiber product and fire-resistant insulating material |
| CN1330575C (en) * | 2005-07-27 | 2007-08-08 | 太原刚玉特种耐火材料有限公司 | Decarbonization method for producing alumina base high purity corundum |
| WO2008072501A1 (en) * | 2006-12-15 | 2008-06-19 | Nippon Light Metal Company, Ltd. | PROCESS FOR PRODUCING HIGH-PURITY α-ALUMINA |
| JP2008150238A (en) * | 2006-12-15 | 2008-07-03 | Nippon Light Metal Co Ltd | Method for production of high-purity alpha-alumina |
| US8124048B2 (en) | 2006-12-15 | 2012-02-28 | Nippon Light Metal Company, Ltd. | Process for producing high-purity α-alumina |
| JP2009235181A (en) * | 2008-03-26 | 2009-10-15 | Hitachi Metals Ltd | Method for manufacturing fluorescent material |
| CN112851309A (en) * | 2021-01-26 | 2021-05-28 | 江苏新时高温材料股份有限公司 | High-thermal-shock low-creep corundum processing technology |
| WO2023073842A1 (en) * | 2021-10-27 | 2023-05-04 | 日本軽金属株式会社 | High-purity microparticle alumina powder |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0637293B2 (en) | 1994-05-18 |
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