JPH024531B2 - - Google Patents
Info
- Publication number
- JPH024531B2 JPH024531B2 JP59229654A JP22965484A JPH024531B2 JP H024531 B2 JPH024531 B2 JP H024531B2 JP 59229654 A JP59229654 A JP 59229654A JP 22965484 A JP22965484 A JP 22965484A JP H024531 B2 JPH024531 B2 JP H024531B2
- Authority
- JP
- Japan
- Prior art keywords
- alumina
- sintered
- pressure
- binder
- molding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 64
- 239000002245 particle Substances 0.000 claims description 21
- 239000011230 binding agent Substances 0.000 claims description 17
- 238000000465 moulding Methods 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 239000008187 granular material Substances 0.000 claims description 7
- 239000013078 crystal Substances 0.000 claims description 6
- 238000009826 distribution Methods 0.000 claims description 5
- 239000002994 raw material Substances 0.000 description 10
- 238000005245 sintering Methods 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000010298 pulverizing process Methods 0.000 description 4
- 239000004372 Polyvinyl alcohol Substances 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000004131 Bayer process Methods 0.000 description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 2
- 238000000748 compression moulding Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 239000004375 Dextrin Substances 0.000 description 1
- 229920001353 Dextrin Polymers 0.000 description 1
- 108010010803 Gelatin Proteins 0.000 description 1
- 229920000084 Gum arabic Polymers 0.000 description 1
- 241000978776 Senegalia senegal Species 0.000 description 1
- 235000010489 acacia gum Nutrition 0.000 description 1
- 239000000205 acacia gum Substances 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
- 238000001354 calcination Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 235000019425 dextrin Nutrition 0.000 description 1
- 229920000159 gelatin Polymers 0.000 description 1
- 239000008273 gelatin Substances 0.000 description 1
- 235000019322 gelatine Nutrition 0.000 description 1
- 235000011852 gelatine desserts Nutrition 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 229940005550 sodium alginate Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Description
〔産業上の利用分野〕
本発明は、アルミナ焼結粒の製造方法に関し、
更に詳しくはアルミナを原料として気孔率が小さ
く、圧縮強度の大きいアルミナ焼結粒を製造する
方法に関するものである。
〔従来の技術〕
アルミナの焼結体はキヤスタブル等の骨材やそ
の他の耐火物として種々の用途がある。従来、ア
ルミナ焼結粒の製造方法としては、バイヤー法ア
ルミナを粉砕し、バインダーを添加して造粒後、
1800℃〜1900℃の高温で焼結させたアルミナを粉
砕し、脱鉄処理あるいは篩い分けによつて適当な
範囲の粒度のものを得る方法がある。
〔発明が解決しようとする問題点〕
しかしながら、この方法では1800℃〜1900℃の
高温で焼結させたアルミナを粉砕するため、大き
な粉砕エネルギーを必要とし、また粉砕機の摩耗
が激しく、しかも粉砕後の脱鉄処理が必要であ
り、アルミナ焼結粒の製造コストが高くなる問題
がある。
〔問題点を解決するための手段〕
本発明者らは、アルミナを500Kg／cm2以上の成
形圧で加圧成形して粉枠し、この粉砕物を1400℃
〜1900℃で焼結させることによりアルミナ焼結粒
を得た場合には、従来の方法に比べて小さい粉砕
エネルギーですみ、粉砕機の摩耗も少なく、脱鉄
処理を必要としないことを見い出し、本発明に到
達したものである。
すなわち、本発明は、アルミナを500Kg／cm2以
上の成形圧で加圧成形して粉砕し、1400℃〜1900
℃の温度で焼結させることを特徴とするアルミナ
焼結粒の製造方法である。
本発明のアルミナ焼結粒の製造方法における原
料としてのアルミナは、バイヤー法によつて得ら
れた水酸化アルミニウムを焼成して得られるアル
ミナを代表例として挙げることができる。原料と
してのアルミナは、α晶サイズが0.3μ〜0.5μのα
―アルミナを10〜100重量％含むものがよい。α
晶サイズが0.3μ〜0.5μのアルミナは焼結性がよ
く、したがつて本発明の原料アルミナに適してい
る。
またバイヤー法によつて得られた水酸化アルミ
ニウムを焼成する際、1200℃以上の高温で焼成す
るとα―アルミナの形で多量に製造でき、工業的
に有利である。α―アルミナは他形のアルミナに
比べて安定であり、硬度も高いので、キヤスタブ
ル等の骨材やその他の耐火物の原料として有効で
ある。したがつて、原料としてのアルミナ中のα
―アルミナが多い方が安定性、硬度等の点で望ま
しいが、最終的に得られるアルミナ焼結粒の用途
に応じて原料としてのアルミナ中のα―アルミナ
含有量は、任意に選定できる。しかし、原料とし
てのアルミナ中のα―アルミナ含有量が少なすぎ
ると、安定性、硬度等の特性に支障が生じるが、
本発明における製造行程中に焼成時の温度条件に
よつて他形のアルミナがα―アルミナに転移する
こともあるので原料としてのアルミナ中のα―ア
ルミナ含有量は10〜100％であればよい。
次に上記のようなアルミナは、バインダーを用
いることなく、あるいは少量のバインダーを用い
て500Kg／cm2以上の成形圧で加圧成形される。成
形圧が500Kg／cm2よりも低いと、アルミナ成形品
の強度が低くなり、加圧成形工程後の粉砕工程、
焼結工程において、成形品が壊れるおそれがある
が、500Kg／cm2以上の成形圧で加圧成形すると、
粉砕工程および焼結工程において、粉砕されやす
いと同時に粉砕後に必要とされる粒径を維持でき
る強度と焼結処理に充分耐えうる強度を有する。
加圧成形に際しては、成形圧や原料としてのア
ルミナの粒度やその成分等によつてバインダーを
用いることなく、あるいは少量のバインダーを用
いるのみで足りる。すなわち、成形圧が高い場
合、あるいはアルミナの粒度が小さい等の条件の
場合、バインダーを用いなくともよく、更に他の
条件の場合でも少量のバインダーで足りる。一般
に転動造粒法では造粒体を連続的に製造すること
ができるが、歩留りが悪く十数mmから粉状のもの
で広い粒度分布となり、多量のバインダーを必要
とするとともに造粒体の乾燥工程を必要とする。
しかし、本発明のように加圧成形後、粉砕する方
法ではバインダーを用いることなく、あるいは極
めて少量のバインダーを用いるのみで足り、乾燥
工程等を有しない。
バインダーとしては、ポリビニルアルコール
（PVA）、カルボキシメチルセルロース（CMC）、
デキストリン、アラビヤゴム、アルギン酸ソー
ダ、リグニンスルホン酸、ニカワ（ゼラチン）、
塩基性塩化アルミニウム〔一般にポリ塩化アルミ
ニウム（PAC）と呼ばれる〕、塩化アルミ、硫酸
アルミなどの公知のバインダーをいずれも使用す
ることができる。これらのバインダーは、アルミ
ナに対し固形分として５重量％以下で充分な強度
を得ることができる。
成形機としては、チルソネータのような圧縮加
工成形機と回転式粉砕機の両方の機能を有する成
形品を用いれば、加圧成形と粉砕とを同時に行う
ことができ、効率的である。勿論通常の加圧成形
機によつて加圧成形した後、粉砕してもよい。
加圧成形物を粉砕するに際しては、0.1〜５
ｍ／ｍ程度に粉砕することが望ましい。粉砕時の
粒径は最終的に得られるアルミナ焼結粒の用途に
応じて任意に選定されるべきであるが、アルミナ
焼結粒の嵩比重、見掛気孔率、圧壊強度等の点か
ら0.1〜５ｍ／ｍ程度の粒度分布が最適である。
次に加圧成形品の粉砕物を焼結させる温度は
1400℃〜1900℃である。焼結温度が1400℃よりも
低いと得られるアルミナ焼結造粒体の強度が不十
分となり、また1400℃〜1900℃で強度に優れたア
ルミナ焼結造粒体が得られ1900℃を超えると加圧
成形品の粉砕物の原形を崩すことになり焼結造粒
体としての不都合なものとなる。なお、加圧成形
品の粉砕物に対し、通常用いられている公知の焼
結助剤を用いることもできる。このような焼結助
剤として、Mgo、MgCl2等を挙げることができ
る。焼結助剤は0.05〜1.0重量％添加すれば十分
である。
〔発明の効果〕
以上のように本発明によれば、アルミナを加圧
成形後、粉砕し、次いで焼結するので造粒後焼結
させたアルミナを粉砕する従来の方法に比べて小
さい粉砕エネルギーですみ、粉砕機の摩耗が少な
く、かつ粉砕機の摩耗による鉄分の混入が極めて
少ないので脱鉄処理が不要である。
〔実施例〕
実施例 １
バイヤー法で得たアルミナを仮焼した、α晶サ
イズが0.3μ〜0.5μのアルミナにMgOを0.5重量％
添加し粉砕後ロール型圧縮造粒機にかけ、乾式
〔バインダー無〕で成形圧1500Kg／cm2で圧縮成形
後粉砕しロータリーキルンで1600℃で焼結させ
た。
得られた、焼結アルミナの粒度分布及び嵩比
重・見掛気孔率は第１表の通りである。
[Industrial Application Field] The present invention relates to a method for producing sintered alumina particles,
More specifically, the present invention relates to a method for producing sintered alumina particles having low porosity and high compressive strength using alumina as a raw material. [Prior Art] Alumina sintered bodies have various uses as aggregates for castables and other refractories. Conventionally, the method for producing sintered alumina granules has been to crush alumina using the Bayer method, add a binder, granulate it, and then
There is a method of pulverizing alumina sintered at a high temperature of 1800° C. to 1900° C., and obtaining particles with a suitable range of particle size by deiron treatment or sieving. [Problems to be Solved by the Invention] However, this method requires a large amount of grinding energy because the alumina is sintered at a high temperature of 1800°C to 1900°C, and the grinder is subject to severe wear. There is a problem in that a subsequent iron removal treatment is required, which increases the manufacturing cost of the alumina sintered grains. [Means for solving the problem] The present inventors pressure-molded alumina at a molding pressure of 500 kg/cm 2 or more to form a powder frame, and heated the pulverized product at 1400°C.
We discovered that when alumina sintered grains are obtained by sintering at ~1900℃, less crushing energy is required compared to conventional methods, there is less wear on the crusher, and there is no need for iron removal treatment. This has led to the present invention. That is, in the present invention, alumina is pressure-molded and pulverized at a molding pressure of 500 kg/cm 2 or more, and then
This is a method for producing sintered alumina grains, which is characterized by sintering at a temperature of °C. A representative example of alumina used as a raw material in the method for producing sintered alumina particles of the present invention is alumina obtained by firing aluminum hydroxide obtained by the Bayer method. Alumina as a raw material is an α crystal with an α crystal size of 0.3μ to 0.5μ.
-Those containing 10 to 100% alumina by weight are preferable. α
Alumina with a crystal size of 0.3μ to 0.5μ has good sinterability and is therefore suitable as the raw material alumina of the present invention. Furthermore, when aluminum hydroxide obtained by the Bayer process is fired at a high temperature of 1200°C or higher, it can be produced in large quantities in the form of α-alumina, which is industrially advantageous. α-Alumina is more stable and hard than other forms of alumina, so it is effective as a raw material for castable aggregates and other refractories. Therefore, α in alumina as a raw material
-Although it is desirable to have a large amount of alumina in terms of stability, hardness, etc., the α-alumina content in the alumina as a raw material can be arbitrarily selected depending on the use of the ultimately obtained sintered alumina particles. However, if the α-alumina content in alumina as a raw material is too low, properties such as stability and hardness will be affected.
During the manufacturing process of the present invention, other forms of alumina may transform into α-alumina depending on the temperature conditions during firing, so the α-alumina content in the alumina as a raw material may be 10 to 100%. . Next, the above alumina is pressure molded without using a binder or with a small amount of binder at a molding pressure of 500 kg/cm 2 or more. If the molding pressure is lower than 500Kg/ cm2 , the strength of the alumina molded product will be low, and the crushing process after the pressure molding process,
There is a risk that the molded product will break during the sintering process, but if it is pressure molded at a molding pressure of 500 kg/cm2 or more
In the crushing process and the sintering process, it is easy to crush, and at the same time has the strength to maintain the required particle size after crushing, and has enough strength to withstand the sintering process. During pressure molding, depending on the molding pressure, the particle size of alumina as a raw material, its components, etc., it is sufficient to use no binder or only a small amount of binder. That is, when the molding pressure is high or when the particle size of alumina is small, it is not necessary to use a binder, and even under other conditions, a small amount of binder is sufficient. Generally, the rolling granulation method allows the continuous production of granules, but the yield is poor and the particle size distribution is wide with particles ranging from 10-10 mm to powder, requiring a large amount of binder, and Requires a drying process.
However, in the method of crushing after pressure molding as in the present invention, it is sufficient to use no binder or only a very small amount of binder, and there is no drying step or the like. As a binder, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC),
Dextrin, gum arabic, sodium alginate, lignin sulfonic acid, glue (gelatin),
Any known binder can be used, such as basic aluminum chloride (commonly referred to as polyaluminum chloride (PAC)), aluminum chloride, aluminum sulfate, and the like. These binders can provide sufficient strength at a solid content of 5% by weight or less based on alumina. As a molding machine, if a molded product having the functions of both a compression molding machine and a rotary pulverizer, such as a Chillsonator, is used, pressure molding and pulverization can be performed simultaneously, which is efficient. Of course, the material may be pulverized after pressure molding using a normal pressure molding machine. When crushing a pressure-molded product, 0.1 to 5
It is desirable to crush the powder to about m/m. The particle size during crushing should be arbitrarily selected depending on the use of the final sintered alumina particles, but it should be 0.1 from the viewpoint of bulk specific gravity, apparent porosity, crushing strength, etc. of the sintered alumina particles. A particle size distribution of about 5 m/m is optimal. Next, the temperature at which the crushed material of the pressure-formed product is sintered is
The temperature is 1400℃~1900℃. If the sintering temperature is lower than 1400°C, the strength of the alumina sintered granules obtained will be insufficient, and if the sintering temperature is between 1400°C and 1900°C, alumina sintered granules with excellent strength will be obtained, but if it exceeds 1900°C, This destroys the original shape of the pulverized pressure-molded product, which is inconvenient as a sintered granule. Incidentally, a commonly used known sintering aid can also be used for the pulverized material of the pressure-molded product. Examples of such sintering aids include Mgo, MgCl 2 and the like. It is sufficient to add the sintering aid in an amount of 0.05 to 1.0% by weight. [Effects of the Invention] As described above, according to the present invention, alumina is pressure-formed, then crushed, and then sintered, so the crushing energy is smaller than in the conventional method of crushing alumina that has been granulated and sintered. There is no need for iron removal treatment because there is little wear on the crusher, and there is very little iron contamination due to wear on the crusher. [Example] Example 1 0.5% by weight of MgO is added to alumina with an α-crystal size of 0.3μ to 0.5μ, which is obtained by calcining alumina obtained by the Bayer process.
After adding and pulverizing, the mixture was applied to a roll-type compression granulator, compressed in a dry manner (without binder) at a molding pressure of 1500 kg/cm 2 , and then pulverized and sintered at 1600°C in a rotary kiln. The particle size distribution, bulk specific gravity, and apparent porosity of the obtained sintered alumina are shown in Table 1.
【表】
MgOの代りにMgCl2を用いた他は上記同様に
して得たアルミナ焼結粒の粒度分布、嵩比重、見
掛気孔率も第１表に示す値とほぼ同じであつた。
実施例 ２
バイヤー法で得たアルミナを焼成した、α晶サ
イズが0.3μ〜0.5μのアルミナにMgOを0.7重量％
添加し、粉砕後、小型プレス機を使用しバインダ
ー法としてPVAを５重量％添加して成形圧1200
Kg／cm2で圧縮成形後粉砕し、ロータリーキルンで
1600℃で焼結させた。
次のような特性の焼結アルミナが得られた。[Table] The particle size distribution, bulk specific gravity, and apparent porosity of the alumina sintered particles obtained in the same manner as above except that MgCl 2 was used instead of MgO were almost the same as the values shown in Table 1. Example 2 0.7% by weight of MgO is added to alumina with an α crystal size of 0.3μ to 0.5μ, which is obtained by firing alumina obtained by the Bayer method.
After adding and pulverizing, 5% by weight of PVA was added as a binder method using a small press machine and the molding pressure was 1200.
After compression molding at Kg/ cm2 , it is crushed and then put in a rotary kiln.
Sintered at 1600℃. Sintered alumina with the following properties was obtained.
【表】
MgOの代りにMgCl2を用いた他は上記同様に
して得たアルミナ焼結粒の特性も第２表に示す値
とほぼ同じであつた。[Table] The properties of the alumina sintered grains obtained in the same manner as above except that MgCl 2 was used instead of MgO were also almost the same as the values shown in Table 2.
Claims (1)
形して粉砕し、この粉砕物を1400℃〜1900℃で焼
結させることを特徴とするアルミナ焼結粒の製造
方法。 ２ 前記アルミナは、α晶サイズが0.3μ〜0.5μの
α―アルミナを10重量％以上含むことを特徴とす
る特許請求の範囲第１項記載のアルミナ焼結粒の
製造方法。 ３ 前記アルミナは、バインダーを用いることな
く加圧成形されることを特徴とする特許請求の範
囲第１項記載のアルミナ焼結粒の製造方法。 ４ 前記アルミナは、５重量％以下のバインダー
が添加された後、加圧成形されることを特徴とす
る特許請求の範囲第１項記載のアルミナ焼結粒の
製造方法。 ５ 加圧成形されたアルミナは、0.1〜５mmの粒
度分布となるように粉砕されることを特徴とする
特許請求の範囲第１項記載のアルミナ焼結粒の製
造方法。[Claims] 1. Production of alumina sintered granules, characterized in that alumina is pressure-molded and pulverized at a molding pressure of 500 kg/cm 2 or more, and the pulverized product is sintered at 1400°C to 1900°C. Method. 2. The method for producing sintered alumina grains according to claim 1, wherein the alumina contains 10% by weight or more of α-alumina having an α crystal size of 0.3μ to 0.5μ. 3. The method for producing sintered alumina particles according to claim 1, wherein the alumina is pressure-formed without using a binder. 4. The method for producing sintered alumina grains according to claim 1, wherein the alumina is pressure-formed after adding 5% by weight or less of a binder. 5. The method for producing sintered alumina particles according to claim 1, wherein the pressure-formed alumina is pulverized to have a particle size distribution of 0.1 to 5 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59229654A JPS61106413A (en) | 1984-10-31 | 1984-10-31 | Production of alumina sintered granule |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59229654A JPS61106413A (en) | 1984-10-31 | 1984-10-31 | Production of alumina sintered granule |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61106413A JPS61106413A (en) | 1986-05-24 |
| JPH024531B2 true JPH024531B2 (en) | 1990-01-29 |
Family
ID=16895585
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59229654A Granted JPS61106413A (en) | 1984-10-31 | 1984-10-31 | Production of alumina sintered granule |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61106413A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5641469A (en) * | 1991-05-28 | 1997-06-24 | Norton Company | Production of alpha alumina |
-
1984
- 1984-10-31 JP JP59229654A patent/JPS61106413A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61106413A (en) | 1986-05-24 |
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