JPS6141849B2 - - Google Patents
Info
- Publication number
- JPS6141849B2 JPS6141849B2 JP53021218A JP2121878A JPS6141849B2 JP S6141849 B2 JPS6141849 B2 JP S6141849B2 JP 53021218 A JP53021218 A JP 53021218A JP 2121878 A JP2121878 A JP 2121878A JP S6141849 B2 JPS6141849 B2 JP S6141849B2
- Authority
- JP
- Japan
- Prior art keywords
- aluminum hydroxide
- seeds
- precipitation
- particle size
- gallium
- 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
Links
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 115
- 238000000034 method Methods 0.000 claims description 55
- 239000002245 particle Substances 0.000 claims description 46
- 238000001556 precipitation Methods 0.000 claims description 44
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 claims description 24
- 229910001388 sodium aluminate Inorganic materials 0.000 claims description 24
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 claims description 21
- 229910052733 gallium Inorganic materials 0.000 claims description 21
- 238000004131 Bayer process Methods 0.000 claims description 7
- 230000000694 effects Effects 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 230000000977 initiatory effect Effects 0.000 claims description 2
- 230000001376 precipitating effect Effects 0.000 claims description 2
- 230000002776 aggregation Effects 0.000 description 27
- 238000005054 agglomeration Methods 0.000 description 15
- 238000004220 aggregation Methods 0.000 description 12
- 238000005189 flocculation Methods 0.000 description 11
- 230000016615 flocculation Effects 0.000 description 11
- 239000011734 sodium Substances 0.000 description 9
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 230000004913 activation Effects 0.000 description 5
- 238000009826 distribution Methods 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- ZNCPFRVNHGOPAG-UHFFFAOYSA-L sodium oxalate Chemical compound [Na+].[Na+].[O-]C(=O)C([O-])=O ZNCPFRVNHGOPAG-UHFFFAOYSA-L 0.000 description 5
- 229940039790 sodium oxalate Drugs 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 238000001479 atomic absorption spectroscopy Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000011002 quantification Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000003723 Smelting Methods 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
- -1 aluminum sulfate Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 229910021513 gallium hydroxide Inorganic materials 0.000 description 1
- DNUARHPNFXVKEI-UHFFFAOYSA-K gallium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Ga+3] DNUARHPNFXVKEI-UHFFFAOYSA-K 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000003860 storage Methods 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
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
- C01F7/144—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by precipitation due to cooling, e.g. as part of the Bayer process
- C01F7/145—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by precipitation due to cooling, e.g. as part of the Bayer process characterised by the use of a crystal growth modifying agent other than aluminium hydroxide seed
-
- 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
- C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
- C01F7/14—Aluminium oxide or hydroxide from alkali metal aluminates
- C01F7/144—Aluminium oxide or hydroxide from alkali metal aluminates from aqueous aluminate solutions by precipitation due to cooling, e.g. as part of the Bayer process
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)
Description
本発明はバイヤー法或はその改良法による水酸
化アルミニウムの製造方法に於いて水酸化アルミ
ニウムの析出工程に添加する種子用水酸化アルミ
ニウムの活性状態を予知し、該活性状態より工程
内のアルミン酸ソーダ溶液中のNa2O／Al2O3のモ
ル比（以下、モル比と称する）等を調整する事よ
り、析出水酸化アルミニウムの粒度を調整する水
酸化アルミニウムの製造方法に関するものであ
る。
バイヤー法或はその改良法により得られる水酸
化アルミニウムの用途は大別してアルミニウムの
電解製錬用原料、硫酸アルミニウム、アルミン酸
ソーダ等のアルミナ化合物用原料であるが、いず
れの用途に於いても、運搬、貯蔵時の作業性、加
工時のハンドリングコスト及びエネルギー価格面
から粒度変化の少ない水酸化アルミニウムが要求
されている。そのため現プロセスに於いては、析
出水酸化アルミニウムの粒度分布の経時変化によ
り、粒度分布の傾向を把握しこれに基づき析出温
度、アルミン酸ソーダ溶液中のモル比、添加種子
量等の析出条件を変更し、或は分級条件を変更す
る事により製品水酸化アルミニウムの粒度を調整
していた。
しかしながら該析出水酸化アルミニウムの粒度
の経時変化を傾向的に把握する方法は粒度が上昇
傾向にあるのか下降傾向にあるのかを判断するの
に極めて長時間を要し、加えて析出条件変更の影
響が製品に表われる迄にも長時間を必要とする
等、条件設定から効果を得る迄に通常１〜２カ月
という長時間を余儀なくされていた。
バイヤー法或はその改良法でアルミン酸ソーダ
溶液からの析出水酸化アルミニウムの粒度は種子
用水酸化アルミニウムの表面活性状態、添加量、
アルミン酸ソーダ溶液中のアルミナの過飽和度、
析出温度等より左右される事は既に公知である。
上記析出水酸化アルミニウムの粒度に与える要
因のうち種子用水酸化アルミニウムの表面活性状
態は析出に及ぼす影響が極めて大なるものである
にもかかわらず、他の因子の如く明確に定量化さ
れた報告は本発明者等の知り得る限り全く無く、
加えてこれが実際の工業的規模の操業に適用され
た報告もない。
しかるに、種子用水酸化アルミニウムの成長は
析出工程において通常の結晶成長と同様に種子表
面上への水酸化アルミニウムの析出と種子用の凝
集からなつており、特にバイヤー工程では凝集が
重大な因子である。
しかして、種子用水酸化アルミニウムの凝集性
能が大きければ単に種子間の凝集による成長が大
きいだけでなく、析出反応中に発生した核が種子
用水酸化アルミニウムと凝集しやすくなり、液中
に安定して懸濁しがたく、単位容積中の種子個数
が減少し、種子１個当りの析出量が増大する。逆
に種子用水酸化アルミニウムの凝集性能が小さけ
れば種子の凝集による成長は小さく反応中に発生
した核も反応液中に安定して懸濁する為、単位容
積中の種子個数は次第に増大する。このように凝
集は水酸化アルミニウムの析出に於いて極めて重
大な因子なのである。
かかる観点より本発明者らは種子用水酸化アル
ミニウムのアルミン酸ソーダ溶液中の凝集性能を
定量化する事が出来れば、種子用水酸化アルミニ
ウムの活性状態を予知する事となり、これを実プ
ロセスでの析出工程に適用するならば、析出水酸
化アルミニウムの粒度調整が極めて迅速に行なえ
るものと考え、種子凝集性能の定量化の確立と水
酸化アルミニウムの析出工程への適用を鋭意研究
した結果、ガリウムドープした水酸化アルミニウ
ムを用いる事により精度よく種子の凝集性能を定
量化せしめ得る事を見出し、これを析出工程での
操業条件変更の目安として用いる事に成功し、本
発明方法を完成するに至つた。
すなわち、本発明はバイヤー法或はその改良法
における水酸化アルミニウムの析出工程に於い
て、該析出工程のアルミン酸ソーダ溶液中に添加
する種子用水酸化アルミニウムを予じめガリウム
ドープした水酸化アルミニウムとアルミン酸ソー
ダ溶液中に添加し、該種子用水酸化アルミニウム
に凝集するガリウムドープした水酸化アルミニウ
ムより種子用水酸化アルミニウムの活性状態を求
め、該活性状態に応じてバイヤー工程における析
出水酸化アルミニウムの粒度に影響を与える因子
の少なくとも１つを調整する事を特徴とする製品
水酸化アルミニウムの粒度調整を目的とした水酸
化アルミニウムの製造方法を提供するにある。
以下、本発明方法を更に具体的に説明する。
本発明において種子用水酸化アルミニウムの凝
集性能はガリウムドープした水酸化アルミニウム
を種子用水酸化アルミニウムと析出工程のアルミ
ン酸ソーダ溶液中に添加し、析出反応を行なわせ
た後、析出水酸化アルミニウムを篩別し、各粒度
分布に於けるガリウムドープされた水酸化アルミ
ニウムの存在量を分折する事により決定する。
本発明方法に用いるガリウムドープした水酸化
アルミニウムは水酸化アルミニウムにガリウムを
含浸、或は共析せしめる等の水酸化アルミニウム
にガリウムを存在せしめたものであれば、特に制
限されるものではないが、ガリウム含有物質、例
えば金属ガリウム、水酸化ガリウム等をアルミン
酸ソーダ溶液中に溶解し、しかる後水酸化アルミ
ニウムと共析させる方法が好ましい。
水酸化アルミニウム中に存在せしめるガリウム
の量は実プロセスにおいて適用する循環種子用水
酸化アルミニウム中に含有されるガリウム量以上
であればよく、特に制限されるものではないが、
通常金属ガリウムとして0.01重量％以上好適には
0.1重量％以上が望ましく、一方上限は特に制限
されるものではないが、通常水酸化アルミニウム
の性状を変えないことが望ましいため約10重量％
以下の範囲が用いられる。
また、ガリウムドープ水酸化アルミニウムの粒
子径は種子用水酸化アルミニウムの凝集性能を知
る必要上、該種子用水酸化アルミニウムより小さ
い事が望ましく、通常５μ以下、好ましくは３μ
以下が使用され、これらは予じめ篩別機等により
整粒されたものが望ましい。
一方、凝集性能を調べる種子用水酸化アルミニ
ウムは、析出工程に添加するものが用いられ、粒
子径は特に制限されるものではないが、ガリウム
ドープされた水酸化アルミニウムの粒子径より大
きい事が望ましく、通常５μ以上、好ましくは20
μ以上で予じめ整粒されたものが用いられる。
本発明方法の実施に於いて、ガリウムドープさ
れた水酸化アルミニウムと種子用水酸化アルミニ
ウムは析出工程に於ける最初の析出槽から導出さ
れたアルミン酸ソーダ溶液（以下、析出開始液と
称す）に添加される。
種子用水酸化アルミニウムに対するガリウムド
ープされた水酸化アルミニウムの量は実プロセス
に於いて適用する種子用水酸化アルミニウム中に
含有されるガリウム量と区別し得る量であればよ
く通常0.01重量％以上、好ましくは0.1〜５重量
％の範囲で行なえばよい。
又、アルミン酸ソーダ溶液に対する水酸化アル
ミニウムの全添加量、析出時間および析出温度は
特に制限されるものではないが、実プロセスの量
比、条件を適用すればよい。
更に、アルミン酸ソーダ溶液としては、上記析
出開始液の他、該溶液と同モル比の合成アルミン
酸ソーダ溶液を用いる事も出来る。
このようにして、アルミン酸ソーダ溶液に添加
されたガリウムドープされた水酸化アルミニウム
は種子用水酸化アルミニウムの活性状態に応じて
種子用水酸化アルミニウムに凝集され、析出する
ので、ロ過分離後析出水酸化アルミニウムを粒度
区分し、各々の粒度範囲の水酸化アルミニウムに
含有されるガリウム濃度を求め、析出前の各粒度
区分に於けるガリウム濃度と比較し、凝集率を算
出すればよい。
凝集率の算出は、例えばアルミン酸ソーダ溶液
１に37μ以上の粒径を有する種子用水酸化アル
ミニウム100ｇ（含有ガリウム量37.5mg）と１〜
３μの粒径を有するガリウムドープさせた水酸化
アルミニウム１ｇ（含有ガリウム量17.5mg）を添
加し析出せしめた後、ロ過分離後水酸化アルミニ
ウムの粒度区分し、各々の粒度範囲に含有される
ガリウム濃度を測定し、その値が粒度10μ以下で
１mg、10〜20μで１mg、20〜37μで５mg、37μ以
上で48mgであればガリウムドープされた水酸化ア
ルミニウムの種子水酸化アルミニウムへの凝集率
は10.5mg／17.5mg×100＝60％として実施すれば
よく、凝集率の高い程、種子は高活性状態を示す
事になる。
析出水酸化アルミニウム中のガリウム濃度の測
定は、公知方法、例えば塩酸溶液中に該析出物を
溶解せしめ原子吸光分析で求めればよい。
本発明方法の実施に際し、上記方法で得られた
種子用水酸化アルミニウムの凝集率より実プロセ
スの析出工程における操業条件は変更される。
例えば、本プロセスでの標準凝集率が30％であ
り、測定凝集率が20％であり、種子用水酸化アル
ミニウムが不活性傾向を示す場合、種子が凝集容
易な操業条件、例えば析出温度を上昇するとか、
アルミナのモル比を低下せしめるとか、添加種子
量を増加する等の操作を実施すればよい。かかる
種子用水酸化アルミニウムが活性状態、或は不活
性状態にある場合の析出条件の変更因子としては
アルミン酸ソーダ溶液中のNa2O／Al2O3のモル
比、析出温度、種子用水酸化アルミニウムの添加
量が挙げられ、これら因子の少なくとも１種以上
を変動せしめる事により所望粒度の水酸化アルミ
ニウムを得る事が出来る。
更に、別法として種子用水酸化アルミニウムが
不活性傾向を示す場合にはアルミン酸ソーダ溶液
中に不純物、通常シユウ酸ソーダ等の有機物が蓄
積され、種子用水酸化アルミニウムに悪影響を与
えている事も考慮されるので、アルミン酸ソーダ
溶液中の不純物を除去する公知方法、例えば冷
却、或いは強塩基性物質を添加しシユウ酸ソーダ
の溶解度を低下し、析出除去せしめる方法、更に
は種子用水酸化アルミニウムを直接洗浄する方法
等の操作を行う事も効果がある。
また、機械的操作、例えば撹拌強度、分級条件
の変更を行う事も考えられる。
これら標準凝集率に対する測定凝集率の差異に
よる実プロセスでの操業条件の変更は各々のプロ
セスにより異なるので日常操業データよりそのプ
ロセスに適した相関を求め決定すればよい。
しかして、かかる凝集率の実プロセスへの適用
に於いては、各々のプロセスの操業条件（例え
ば、アルミン酸ソーダ溶液中のモル比1.4〜2.1、
析出温度40〜80℃、種子用水酸化アルミニウムの
添加量50〜500ｇ/、析出時間20〜100時間等）、
或は所望粒度が異なるので全バイヤー工程に適用
し得る凝集率を一義的に決める事は出来ない。
しかしながら、個々のプロセスに於いて一定期
間、種子用水酸化アルミニウムの凝集率と析出水
酸化アルミニウムの粒度分布を調べる事により所
望粒度分布の析出水酸化アルミニウムを得る事の
できる最適凝集率は簡単に見出されるので、これ
を個々のプロセスにおける標準凝集率と決定し、
以降の所望粒度の析出水酸化アルミニウムを得る
ための操業指標と成しうる事は容易である。
以上、詳述したように本発明方法は、析出工程
に添加する種子用水酸化アルミニウムの活性状態
を凝集率として定量化し、現状種子の活性状態傾
向を把握し、これをバイヤープロセスの操業条件
変更の指標となす事に初めて成功したもので、従
来１〜２カ月必要であつた析出水酸化アルミニウ
ムの粒度調整が数日間で可能となり極めて迅速か
つ適切に操業を行なう事ができるのみならず、粒
度変動幅も減ずる事を可能とならしめたもので、
その工業的価値は頗る大なるものである。
以下、本発明方法を実施例により具体的に説明
するが、本発明は以下の実施例により何ら制限を
受けるものではない。
実施例 １
実験−１として内容積1.5の撹拌機付容器
に、Na2O109.5ｇ/、Al2O3119.2ｇ/、Ga0.1
ｇ/の組成を有するアルミン酸ソーダ溶液１
と粒度37μ以上でガリウム含有率0.0055％の種子
水酸化アルミニウム100ｇおよび粒度１〜３μで
ガリウム含有率1.0％のガリウムドープ水酸化ア
ルミニウム１ｇを添加し温度70℃、撹拌速度
120r.p.m.の析出条件下で24時間析出操作を実施
した。その結果、Na2O116.6ｇ/、Al2O364.2
ｇ/、Ga0.1ｇ/の組成を有する反応終了溶液
と191.0ｇ析出水酸化アルミニウムが得られた。
また、実験−２として粒度37μ以上でガリウム
含有率0.0057％の上記種子水酸化アルミニウムと
は実プロセスからの採取時間の異なる種子用水酸
化アルミニウム100ｇを用いた他は実験−１と同
様の条件で析出操作を実施した。その結果
Na2O117.0ｇ/、Al2O363.7ｇ/、Ga0.1ｇ/
の組成を有する反応終了液と192.1ｇの析出水酸
化アルミニウムが得られた。
次いで、実験１、２より得られた析出水酸化ア
ルミニウムを第１表に示す粒度に篩別し、各粒度
毎に原子吸光法によりガリウム濃度を測定した。
その結果を第１表に示す。
The present invention predicts the activation state of aluminum hydroxide for seeds added to the precipitation step of aluminum hydroxide in a method for producing aluminum hydroxide using the Bayer method or an improved method thereof, and uses the activation state to predict sodium aluminate in the process. The present invention relates to a method for producing aluminum hydroxide in which the particle size of precipitated aluminum hydroxide is adjusted by adjusting the molar ratio of Na 2 O/Al 2 O 3 (hereinafter referred to as the molar ratio) in a solution. The uses of aluminum hydroxide obtained by the Bayer method or its improved method can be broadly divided into raw materials for electrolytic smelting of aluminum, raw materials for alumina compounds such as aluminum sulfate, and sodium aluminate. Aluminum hydroxide with little change in particle size is required from the viewpoint of workability during transportation and storage, handling costs during processing, and energy costs. Therefore, in the current process, the tendency of the particle size distribution is determined by observing changes over time in the particle size distribution of precipitated aluminum hydroxide, and based on this, the precipitation conditions such as the precipitation temperature, molar ratio in the sodium aluminate solution, and amount of added seeds are determined. The particle size of the product aluminum hydroxide was adjusted by changing the classification conditions. However, the method of grasping trends in the grain size of precipitated aluminum hydroxide over time requires a very long time to judge whether the grain size is increasing or decreasing, and in addition, the influence of changes in precipitation conditions It takes a long time for this to appear in the product, and it usually takes a long time of 1 to 2 months from setting the conditions to obtaining the effect. The particle size of aluminum hydroxide precipitated from a sodium aluminate solution using the Bayer method or its modified method is determined by the surface activity state of aluminum hydroxide for seeds, the amount added,
Supersaturation of alumina in sodium aluminate solution,
It is already known that it is influenced by the precipitation temperature, etc. Among the factors that affect the particle size of precipitated aluminum hydroxide, the surface activity state of aluminum hydroxide for seeds has an extremely large effect on precipitation, but there are no reports that have clearly quantified it like other factors. As far as the inventors know, there is no
In addition, there are no reports of this being applied to actual industrial-scale operations. However, the growth of aluminum hydroxide for seeds consists of precipitation of aluminum hydroxide on the seed surface and agglomeration of seeds, similar to normal crystal growth in the precipitation process, and aggregation is particularly important in the Bayer process. . Therefore, if the flocculation performance of aluminum hydroxide for seeds is high, not only will the growth due to aggregation between seeds be large, but also the nuclei generated during the precipitation reaction will be more likely to aggregate with aluminum hydroxide for seeds, making them stable in the liquid. It is difficult to suspend, the number of seeds per unit volume decreases, and the amount of precipitation per seed increases. On the other hand, if the aggregation performance of aluminum hydroxide for seeds is low, the growth due to aggregation of seeds will be small and the nuclei generated during the reaction will be stably suspended in the reaction solution, so the number of seeds in a unit volume will gradually increase. Thus, agglomeration is a very important factor in the precipitation of aluminum hydroxide. From this point of view, if the present inventors were able to quantify the flocculation performance of aluminum hydroxide for seeds in a sodium aluminate solution, they would be able to predict the active state of aluminum hydroxide for seeds, and this would be useful in determining the precipitation rate in the actual process. If applied to the process, the particle size of precipitated aluminum hydroxide can be adjusted extremely quickly, and as a result of intensive research on establishing the quantification of seed flocculation performance and applying it to the aluminum hydroxide precipitation process, we found that gallium doped They discovered that the flocculation performance of seeds could be quantified with high precision by using aluminum hydroxide, and succeeded in using this as a guideline for changing operating conditions in the precipitation process, leading to the completion of the method of the present invention. . That is, the present invention involves the step of precipitating aluminum hydroxide in the Bayer method or an improved method thereof, in which the aluminum hydroxide for seeds added to the sodium aluminate solution in the precipitation step is mixed with aluminum hydroxide doped with gallium in advance. The active state of the aluminum hydroxide for seeds is determined from the gallium-doped aluminum hydroxide that is added to the sodium aluminate solution and aggregates in the aluminum hydroxide for seeds, and the particle size of the aluminum hydroxide precipitated in the Bayer process is determined according to the active state. An object of the present invention is to provide a method for producing aluminum hydroxide for the purpose of adjusting the particle size of a product aluminum hydroxide, which is characterized by adjusting at least one influencing factor. The method of the present invention will be explained in more detail below. In the present invention, the flocculation performance of aluminum hydroxide for seeds is determined by adding gallium-doped aluminum hydroxide to aluminum hydroxide for seeds and a sodium aluminate solution in the precipitation step, causing a precipitation reaction, and then sieving the precipitated aluminum hydroxide. The amount of gallium-doped aluminum hydroxide present in each particle size distribution is determined by analysis. The gallium-doped aluminum hydroxide used in the method of the present invention is not particularly limited as long as gallium is present in aluminum hydroxide, such as by impregnating or eutectoiding aluminum hydroxide with gallium. A preferred method is to dissolve a gallium-containing substance, such as metallic gallium, gallium hydroxide, etc., in a sodium aluminate solution and then eutectoid it with aluminum hydroxide. The amount of gallium present in the aluminum hydroxide is not particularly limited, as long as it is greater than or equal to the amount of gallium contained in the aluminum hydroxide for circulating seeds applied in the actual process.
Usually 0.01% by weight or more as metallic gallium is preferred.
It is preferably 0.1% by weight or more, and the upper limit is not particularly limited, but it is usually about 10% by weight since it is desirable not to change the properties of aluminum hydroxide.
The following ranges are used: In addition, the particle size of gallium-doped aluminum hydroxide is preferably smaller than that of aluminum hydroxide for seeds, as it is necessary to know the flocculation performance of aluminum hydroxide for seeds, and is usually 5μ or less, preferably 3μ.
The following are used, and these are preferably sized in advance using a sieve or the like. On the other hand, the aluminum hydroxide for seeds to be tested for flocculation performance is added to the precipitation process, and the particle size is not particularly limited, but it is preferably larger than the particle size of gallium-doped aluminum hydroxide. Usually 5μ or more, preferably 20
Those that have been pre-sized to a particle size of μ or more are used. In carrying out the method of the present invention, gallium-doped aluminum hydroxide and seed aluminum hydroxide are added to a sodium aluminate solution (hereinafter referred to as precipitation starting solution) drawn out from the first precipitation tank in the precipitation process. be done. The amount of gallium-doped aluminum hydroxide relative to the aluminum hydroxide for seeds may be any amount that can be distinguished from the amount of gallium contained in the aluminum hydroxide for seeds applied in the actual process, usually 0.01% by weight or more, preferably 0.01% by weight or more. It may be carried out in a range of 0.1 to 5% by weight. Further, the total amount of aluminum hydroxide added to the sodium aluminate solution, the precipitation time, and the precipitation temperature are not particularly limited, but the ratio and conditions of the actual process may be applied. Furthermore, as the sodium aluminate solution, in addition to the above-mentioned precipitation initiating solution, a synthetic sodium aluminate solution having the same molar ratio as the solution can also be used. In this way, the gallium-doped aluminum hydroxide added to the sodium aluminate solution is aggregated and precipitated into aluminum hydroxide for seeds depending on the activation state of the aluminum hydroxide for seeds. It is sufficient to classify the aluminum into particle sizes, determine the gallium concentration contained in aluminum hydroxide in each particle size range, and compare it with the gallium concentration in each particle size category before precipitation to calculate the agglomeration rate. To calculate the aggregation rate, for example, add 100 g of aluminum hydroxide for seeds (37.5 mg of gallium content) having a particle size of 37μ or more to 1 of the sodium aluminate solution and 1 to 1.
After adding 1 g of gallium-doped aluminum hydroxide (containing 17.5 mg of gallium) having a particle size of 3 μm and allowing it to precipitate, the aluminum hydroxide was separated by filtration and divided into particle sizes, and the gallium contained in each particle size range was determined. Measure the concentration, and if the value is 1 mg for particles with a particle size of 10 μ or less, 1 mg for 10-20 μ, 5 mg for 20-37 μ, and 48 mg for 37 μ or more, the aggregation rate of gallium-doped aluminum hydroxide to seed aluminum hydroxide is It may be carried out at 10.5 mg/17.5 mg x 100 = 60%, and the higher the aggregation rate, the more active the seeds will be. The concentration of gallium in the precipitated aluminum hydroxide can be measured by a known method, for example, by dissolving the precipitate in a hydrochloric acid solution and performing atomic absorption spectrometry. When carrying out the method of the present invention, the operating conditions in the precipitation step of the actual process are changed based on the agglomeration rate of aluminum hydroxide for seeds obtained by the above method. For example, if the standard flocculation rate in this process is 30%, the measured flocculation rate is 20%, and the aluminum hydroxide for seeds shows a tendency to inertness, then the operating conditions that facilitate the flocculation of the seeds, such as increasing the precipitation temperature, And,
Operations such as lowering the molar ratio of alumina or increasing the amount of seeds added may be performed. When the aluminum hydroxide for seeds is in an active state or an inactive state, the factors that change the precipitation conditions include the molar ratio of Na 2 O / Al 2 O 3 in the sodium aluminate solution, the precipitation temperature, and the aluminum hydroxide for seeds. Aluminum hydroxide having a desired particle size can be obtained by varying at least one of these factors. Furthermore, as an alternative method, if aluminum hydroxide for seeds shows a tendency to be inactive, consider that impurities, usually organic substances such as sodium oxalate, accumulate in the sodium aluminate solution and have a negative impact on the aluminum hydroxide for seeds. Therefore, there are known methods for removing impurities in the sodium oxalate solution, such as cooling or adding a strong basic substance to lower the solubility of sodium oxalate and removing the precipitate. It is also effective to perform operations such as cleaning methods. It is also conceivable to perform mechanical operations such as changing the stirring intensity and classification conditions. Changes in operating conditions in the actual process due to differences in the measured agglomeration rate with respect to the standard aggregation rate vary depending on each process, so a correlation suitable for the process may be found and determined from daily operation data. Therefore, in applying such agglomeration rate to an actual process, the operating conditions of each process (for example, molar ratio in the sodium aluminate solution of 1.4 to 2.1,
(Precipitation temperature 40-80℃, amount of aluminum hydroxide added for seeds 50-500g/, precipitation time 20-100 hours, etc.)
Alternatively, since the desired particle size differs, it is not possible to unambiguously determine the agglomeration rate that can be applied to all Bayer processes. However, by examining the agglomeration rate of aluminum hydroxide for seeds and the particle size distribution of precipitated aluminum hydroxide for a certain period in each individual process, it is easy to find the optimum aggregation rate that can obtain precipitated aluminum hydroxide with the desired particle size distribution. Therefore, this is determined as the standard agglomeration rate for each individual process, and
This can easily be used as an operational indicator for obtaining precipitated aluminum hydroxide with a desired particle size. As detailed above, the method of the present invention quantifies the active state of aluminum hydroxide for seeds added to the precipitation process as the agglomeration rate, grasps the current trend of the active state of seeds, and uses this to change the operating conditions of the Bayer process. This is the first time that we have succeeded in using it as an indicator, and it is now possible to adjust the particle size of precipitated aluminum hydroxide in a few days, which previously required 1 to 2 months.It not only allows for extremely quick and appropriate operations, but also allows for a wider range of particle size fluctuations. This has made it possible to reduce the
Its industrial value is enormous. EXAMPLES Hereinafter, the method of the present invention will be specifically explained using examples, but the present invention is not limited in any way by the following examples. Example 1 As Experiment-1, 109.5 g of Na 2 O, 119.2 g of Al 2 O 3 , and 0.1 Ga were placed in a container with an internal volume of 1.5 and equipped with a stirrer.
Sodium aluminate solution with a composition of g/1
100g of seed aluminum hydroxide with a particle size of 37μ or more and a gallium content of 0.0055% and 1g of gallium-doped aluminum hydroxide with a particle size of 1 to 3μ and a gallium content of 1.0% were added, and the mixture was heated at 70°C and stirred at a stirring speed.
The precipitation operation was carried out for 24 hours under precipitation conditions of 120 rpm. As a result, Na 2 O 116.6g/, Al 2 O 3 64.2
A reaction-completed solution having a composition of Ga/0.1 g/ and 191.0 g of precipitated aluminum hydroxide were obtained. In addition, in Experiment 2, 100 g of seed aluminum hydroxide with a particle size of 37μ or more and a gallium content of 0.0057% was used, and the collection time from the actual process was different from that of the seed aluminum hydroxide. The operation was carried out. the result
Na 2 O 117.0g/, Al 2 O 3 63.7g/, Ga 0.1g/
A reaction completed liquid having a composition of 192.1 g of precipitated aluminum hydroxide was obtained. Next, the precipitated aluminum hydroxide obtained in Experiments 1 and 2 was sieved into the particle sizes shown in Table 1, and the gallium concentration was measured for each particle size by atomic absorption spectrometry.
The results are shown in Table 1.
【表】
第１表から明らかな様に、実験−１で用いた種
子用水酸化アルミニウムにはガリウムドープ水酸
化アルミニウムの５％しか凝集していないが、実
験−２で用いた種子用水酸化アルミニウムにはガ
リウムドープ水酸化アルミニウムの45％が凝集し
ている。この事より、本発明の手法により、種子
水酸化アルミニウムの凝集性能（活性状態）の比
較定量ができる事が明らかである。
実施例 ２
析出開始時の液組成がNa2O111.7ｇ/、
Al2O3105.0ｇ/、Na2C2O46.1ｇ/よりなるア
ルミン酸ソーダ溶液に析出温度70℃で種子用水酸
化アルミニウム75ｇ/を添加し、析出時間48時
間で析出反応終了の液組成がNa2O119.1ｇ/
Al2O371.1ｇ/Na2C2O42.2ｇ/で液温が60℃と
なる実質的にほぼ同条件で２種のプロセスを稼動
せしめ、析出水酸化アルミニウムの粒度傾向を観
察すると伴に、本発明方法の凝集率により種子用
水酸化アルミニウムの活性状態を予知し、該工程
に均一粒度の析出水酸化アルミニウムを得るため
の操業条件変更の目安に用いた。
その結果を第１図および第２図に示す。
第１図は析出水酸化アルミニウムの中心粒径の
経時変化を示すものであり縦軸は析出水酸化アル
ミニウムの中心粒径を表わし、横軸は日数を表わ
す。第２図は第１図と同時期における種子用水酸
化アルミニウムの凝集率を示すもので、凝集率の
測定法は実施例１と同様に実施した。尚、図中実
線は凝集率を操業目安とし操業条件を調整したプ
ロセス挙動、破線は無操作のプロセス挙動を示
す。
第１図および第２図の比較より、凝集率が低下
しはじめる点Ｑ−Ｒの種子を用いた析出水酸化ア
ルミニウムは、２日後、すなわち析出時間にほぼ
比例して中心粒径が第１図点Ｓ−T′間に表わさ
れる如く下向傾向を示している。一方実線に於い
ては点Ｒの凝集率を基準に点Ｓで析出開始液中の
シユウ酸ソーダを冷却除去することによりシユウ
酸ソーダ濃度を2.8ｇ/に低下せしめたのである
が、この場合には第１図Ｓ−Ｔ間により理解され
る如く、中心粒径の変動は極めてわずかである。
これらより明らかな如く、本発明方法の凝集率
により種子用水酸化アルミニウムの活性状態を予
知し、バイヤー工程に適用する方法によれば、極
めて迅速かつ精度よく析出水酸化アルミニウムの
粒度調整が可能となる事が理解される。[Table] As is clear from Table 1, only 5% of the gallium-doped aluminum hydroxide aggregated in the aluminum hydroxide for seeds used in Experiment-1, but in the aluminum hydroxide for seeds used in Experiment-2. 45% of the gallium-doped aluminum hydroxide is agglomerated. From this, it is clear that the method of the present invention allows comparative quantification of the flocculation performance (active state) of seed aluminum hydroxide. Example 2 The liquid composition at the start of precipitation was 111.7 g/Na 2 O,
75 g of aluminum hydroxide for seeds was added to a sodium aluminate solution consisting of 105.0 g of Al 2 O 3 and 6.1 g of Na 2 C 2 O 4 at a precipitation temperature of 70°C, and the precipitation reaction was completed in 48 hours. is Na 2 O119.1g/
The two processes were operated under substantially the same conditions with 71.1 g of Al 2 O 3 / 2.2 g of Na 2 C 2 O 4 / and a liquid temperature of 60°C, and the particle size trends of precipitated aluminum hydroxide were observed. In addition, the agglomeration rate of the method of the present invention was used to predict the activation state of aluminum hydroxide for seeds, and was used as a guideline for changing operating conditions in order to obtain precipitated aluminum hydroxide with a uniform particle size in the process. The results are shown in FIGS. 1 and 2. FIG. 1 shows the change over time in the central particle size of precipitated aluminum hydroxide, where the vertical axis represents the central particle size of precipitated aluminum hydroxide, and the horizontal axis represents the number of days. FIG. 2 shows the aggregation rate of aluminum hydroxide for seeds at the same time as in FIG. 1, and the aggregation rate was measured in the same manner as in Example 1. In addition, the solid line in the figure shows the process behavior when the operating conditions were adjusted using the agglomeration rate as a guideline for operation, and the broken line shows the process behavior without any operation. From a comparison between Figures 1 and 2, it is clear that the center particle size of aluminum hydroxide precipitated using seeds at the point Q-R, where the agglomeration rate begins to decrease, is approximately proportional to the precipitation time after 2 days, that is, the center particle size is approximately proportional to the precipitation time as shown in Figure 1. It shows a downward trend as shown between points S-T'. On the other hand, in the solid line, the sodium oxalate concentration was reduced to 2.8 g/by cooling and removing the sodium oxalate in the precipitation starting liquid at point S based on the aggregation rate at point R. As can be understood from the section ST in FIG. 1, the variation in the central grain size is extremely small. As is clear from the above, according to the method of the present invention, which predicts the activation state of aluminum hydroxide for seeds based on the agglomeration rate and applies it to the Bayer process, it is possible to adjust the particle size of precipitated aluminum hydroxide extremely quickly and accurately. things are understood.
第１図は本明細書中の実施例２の条件における
析出工程での析出水酸化アルミニウムの中心粒径
の経時変化を示し、第２図は析出水酸化アルミニ
ウムの凝集率を示す。
FIG. 1 shows the change over time in the center particle size of precipitated aluminum hydroxide in the precipitation step under the conditions of Example 2 in this specification, and FIG. 2 shows the agglomeration rate of precipitated aluminum hydroxide.
Claims (1)
ルミニウムの析出工程において、該析出工程のア
ルミン酸ソーダ溶液中に添加する種子用水酸化ア
ルミニウムを、予じめガリウムドープした水酸化
アルミニウムとアルミン酸ソーダ溶液中に添加
し、該種子用水酸化アルミニウムと凝集するガリ
ウムドープした水酸化アルミニウムより種子用水
酸化アルミニウムの活性状態を求め、該活性状態
に応じて、バイヤー工程における析出水酸化アル
ミニウムの粒度に影響を与える因子の少くとも１
つを調整する事を特徴とする水酸化アルミニウム
の製造方法。 ２ バイヤー工程における析出水酸化アルミニウ
ムの粒度に影響を与える因子が、本文中に記載す
る析出開始液のモル比、析出温度、種子用水酸化
アルミニウムの添加量、バイヤー工程中のアルミ
ン酸ソーダ溶液中の不純物の濃度、撹拌強度およ
び分級条件からなる特許請求の範囲第１項記載の
方法。[Claims] 1. In the step of precipitating aluminum hydroxide in the Bayer method or its improved method, the aluminum hydroxide for seeds added to the sodium aluminate solution in the precipitation step is aluminum hydroxide doped with gallium in advance. The activity state of the aluminum hydroxide for seeds is determined from the gallium-doped aluminum hydroxide that is added to the sodium aluminate solution and aggregated with the aluminum hydroxide for seeds. At least one of the factors influencing particle size
A method for producing aluminum hydroxide, characterized by adjusting the following: 2 Factors that affect the particle size of precipitated aluminum hydroxide in the Bayer process include the molar ratio of the precipitation initiating solution, the precipitation temperature, the amount of aluminum hydroxide added for seeds, and the amount of aluminum hydroxide in the sodium aluminate solution during the Bayer process. The method according to claim 1, which comprises impurity concentration, stirring intensity, and classification conditions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2121878A JPS54112798A (en) | 1978-02-24 | 1978-02-24 | Manufacture of aluminum hydroxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2121878A JPS54112798A (en) | 1978-02-24 | 1978-02-24 | Manufacture of aluminum hydroxide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS54112798A JPS54112798A (en) | 1979-09-03 |
| JPS6141849B2 true JPS6141849B2 (en) | 1986-09-18 |
Family
ID=12048861
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2121878A Granted JPS54112798A (en) | 1978-02-24 | 1978-02-24 | Manufacture of aluminum hydroxide |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS54112798A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3921054A1 (en) * | 1989-06-27 | 1991-01-03 | Linde Ag | METHOD FOR PRODUCING CO (DOWN ARROW) 2 (DOWN ARROW) GRANULES |
-
1978
- 1978-02-24 JP JP2121878A patent/JPS54112798A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54112798A (en) | 1979-09-03 |
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