JP3449675B2 - Method for recovering silicon fluoride from phosphoric acid production process - Google Patents
Method for recovering silicon fluoride from phosphoric acid production processInfo
- Publication number
- JP3449675B2 JP3449675B2 JP24289196A JP24289196A JP3449675B2 JP 3449675 B2 JP3449675 B2 JP 3449675B2 JP 24289196 A JP24289196 A JP 24289196A JP 24289196 A JP24289196 A JP 24289196A JP 3449675 B2 JP3449675 B2 JP 3449675B2
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- JP
- Japan
- Prior art keywords
- sulfuric acid
- phosphoric acid
- acid
- sif
- phosphate rock
- 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.)
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、燐酸製造プロセス
からフッ化ケイ素（以下、単にＳｉＦ４と記す）を回収
する方法に関する。TECHNICAL FIELD The present invention relates to a method for recovering silicon fluoride (hereinafter simply referred to as SiF 4 ) from a phosphoric acid production process.
【０００２】[0002]
【従来の技術】ＳｉＦ４は、含フッ素アモルファスシリ
コン膜の原料として、あるいは光ファイバー用配線の原
料として使用されている。この製造方法も数多く知られ
ており、代表的なものとしては以下の方法が公知であ
る。2. Description of the Related Art SiF 4 is used as a raw material for a fluorine-containing amorphous silicon film or as a raw material for optical fiber wiring. Many manufacturing methods are known, and the following methods are known as typical ones.
【０００３】（１） ＨＦとＳｉＯ２との反応
濃硫酸存在下でフッ酸（ＨＦ）と酸化ケイ素（Ｓｉ
Ｏ２）を反応させる方法（特公昭５９−３４１３０号公
報）が知られている。
(1) Reaction of HF and SiO 2 Hydrofluoric acid (HF) and silicon oxide (Si) in the presence of concentrated sulfuric acid.
A method of reacting O 2 ) (Japanese Patent Publication No. 59-34130) is known.
【０００４】（２） 金属珪弗化物の熱分解反応
珪弗化ソーダ（Ｎａ２ＳｉＦ６）あるいは珪弗化バリウ
ム（ＢａＳｉＦ６）を熱分解する方法は副生物を生じな
い為、高純度のＳｉＦ４が得られるが、減圧下での熱分
解が必要で、連続的なプロセスの設計が困難で、高コス
トとなる。
Ｎａ２ＳｉＦ６ → ＳｉＦ４＋２ＮａＦ ・・・ （２）
ＢａＳｉＦ６ → ＳｉＦ４＋ＢａＦ２ ・・・ （３）(2) Thermal decomposition reaction of metal silicofluoride Since the method of thermally decomposing sodium silicofluoride (Na 2 SiF 6 ) or barium silicofluoride (BaSiF 6 ) does not produce by-products, high-purity SiF 4 is obtained, but thermal decomposition under reduced pressure is required, and it is difficult to design a continuous process, resulting in high cost. Na 2 SiF 6 → SiF 4 + 2NaF (2) BaSiF 6 → SiF 4 + BaF 2 (3)
【０００５】（３） 珪フッ化水素酸水溶液の分解反応
珪フッ化水素酸水溶液（Ｈ２ＳｉＦ６）を濃硫酸中で分
解する方法も以前から良く知られているが、珪フッ化水
素酸水溶液の濃度が、通常１５〜４０％であることか
ら、多量の硫酸を必要とする為、経済性や処理方法など
に問題がある。
(3) Decomposition reaction of hydrosilicofluoric acid aqueous solution A method of decomposing hydrosilicofluoric acid aqueous solution (H 2 SiF 6 ) in concentrated sulfuric acid has been well known for a long time. Since the concentration of the aqueous solution is usually 15 to 40%, a large amount of sulfuric acid is required, which causes problems in economic efficiency and treatment method.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、燐酸
製造プロセスからＳｉＦ４を安価に回収する方法を提供
することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a method for recovering SiF 4 at low cost from a phosphoric acid manufacturing process.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、鋭意検討
を重ねた結果、燐鉱石と硫酸から燐酸を製造する工程
で、酸化ケイ素を用いることにより燐酸製造プロセスか
ら排出されるＳｉＦ４を、連続的に回収し、コストの低
減を図ることを見い出した。As a result of intensive studies, the inventors of the present invention have found that SiF 4 discharged from the phosphoric acid production process by using silicon oxide is produced in the step of producing phosphoric acid from phosphate rock and sulfuric acid. , And found that they can be continuously collected and cost can be reduced.
【０００８】即ち、本発明は燐鉱石と硫酸液を接触させ
燐酸を製造するプロセスにおいて、該燐鉱石と該硫酸液
を接触する際に酸化ケイ素を加え、得られた粗燐酸を濃
縮し、発生する蒸気あるいは凝縮液中の珪フッ化水素酸
を濃硫酸にて分解し、フッ化ケイ素を得ることを特徴と
する燐酸製造プロセスからフッ化ケイ素を回収する方法
に関する。That is, according to the present invention, in the process of producing phosphoric acid by contacting a phosphate rock with a sulfuric acid solution, silicon oxide is added at the time of contacting the phosphate rock with the sulfuric acid solution, and the obtained crude phosphoric acid is concentrated to generate The present invention relates to a method for recovering silicon fluoride from a phosphoric acid production process, characterized in that hydrofluoric silicic acid in the vapor or condensate is decomposed with concentrated sulfuric acid to obtain silicon fluoride.
【０００９】[0009]
【発明の実施の形態】以下、本発明を詳細に説明する。
本発明のＳｉＦ４の回収プロセスは、燐酸製造プロセス
が燐鉱石を原料とし、燐酸を生産する能力を有するプロ
セスにおいて有用に利用できる。燐鉱石の主成分を化学
式で示すとＣａ１０（ＰＯ４）６Ｆ２で表され、一般的
に、この燐鉱石と硫酸液を反応槽で攪拌することによっ
て、下式（５）に示すように二水石膏と燐酸液が得られ
る。
Ｃａ１０（ＰＯ４）６Ｆ２＋１０Ｈ２ＳＯ４＋２０Ｈ２Ｏ
→ １０ＣａＳＯ４・２Ｈ２Ｏ＋６Ｈ３ＰＯ４＋２ＨＦ ・・・（５）BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
INDUSTRIAL APPLICABILITY The SiF 4 recovery process of the present invention can be effectively used in a process in which a phosphoric acid manufacturing process has a capability of producing phosphoric acid by using phosphate rock as a raw material. The main component of the phosphate rock is represented by the chemical formula Ca 10 (PO 4 ) 6 F 2 , and generally, by stirring the phosphate rock and the sulfuric acid solution in the reaction tank, as shown in the following formula (5), Gypsum dihydrate and phosphoric acid solution are obtained. Ca 10 (PO 4) 6 F 2 + 10H 2 SO 4 + 20H 2 O → 10CaSO 4 · 2H 2 O + 6H 3 PO 4 + 2HF ··· (5)
【００１０】本発明では、この主反応に酸化ケイ素を加
えることによって（５）式で生成するＨＦを、下式
（６）に示すように珪フッ化水素酸とすることにある。
６ＨＦ＋ＳｉＯ２ → Ｈ２ＳｉＦ６＋２Ｈ２０ ・・・ （６）
酸化ケイ素の使用量は、燐鉱石中の主成分（Ｃａ
１０（ＰＯ４）６Ｆ２）１モルに対して０．３４モル以
下、好ましくは０．３２〜０．３３の範囲で加えるのが
好適である。酸化ケイ素の量が０．３４モルを超える
と、副生する石膏と燐酸分の分離が悪化するので好まし
くない。In the present invention, HF produced by the formula (5) by adding silicon oxide to the main reaction is hydrofluoric acid as shown by the following formula (6). 6HF + SiO 2 → H 2 SiF 6 + 2H 2 0 (6) The amount of silicon oxide used is the main component (Ca
It is suitable to add 0.34 mol or less, preferably 0.32 to 0.33, per mol of 10 (PO 4 ) 6 F 2 ). If the amount of silicon oxide exceeds 0.34 mol, separation of gypsum and phosphoric acid by-product is deteriorated, which is not preferable.
【００１１】次に、これを遠心分離器によって、珪フッ
化水素酸を含む粗燐酸と石膏とに分離される。この粗燐
酸液を、エバポレーターを用い減圧下で加熱することに
よって、粗燐酸が濃縮され、また一方、水を含む珪フッ
化水素酸の蒸気が発生する。本発明は、この水を含む珪
フッ化水素酸を回収し、濃硫酸に接触させ（４）式に示
す分解反応を行う。そして濃硫酸は、図１の工程図に示
すように、水を含む珪フッ化水素酸と接触した後、フッ
化水素及び水を混在し、初期工程の燐鉱石との反応用と
して使用するので、効率よく、コストも大幅に削減でき
る。Next, this is separated into crude phosphoric acid containing hydrosilicofluoric acid and gypsum by a centrifugal separator. By heating this crude phosphoric acid solution under reduced pressure using an evaporator, the crude phosphoric acid is concentrated, and, on the other hand, steam of hydrosilicofluoric acid containing water is generated. In the present invention, this hydrosilicofluoric acid containing water is recovered and brought into contact with concentrated sulfuric acid to carry out the decomposition reaction represented by the formula (4). As shown in the process diagram of FIG. 1, the concentrated sulfuric acid is used for reaction with the phosphate rock in the initial step after contacting with hydrosilicofluoric acid containing water and then mixing hydrogen fluoride and water. Efficient and cost can be reduced significantly.
【００１２】次に、水を含む珪フッ化水素酸を、濃硫酸
に接触させる反応容器について説明する。反応容器の形
状は、特に限定するものではないが一般的な吸収搭また
は槽型反応器が使用できる。また、接液部、接ガス部は
フッ素樹脂でコーテングあるいはライニングすることが
望ましい。Next, the reaction vessel in which hydrosilicofluoric acid containing water is brought into contact with concentrated sulfuric acid will be described. The shape of the reaction vessel is not particularly limited, but a general absorption tower or a tank reactor can be used. Further, it is desirable that the liquid contact portion and the gas contact portion are coated or lined with a fluororesin.
【００１３】吸収塔は、図２に示す円筒状の反応器で、
上部より濃硫酸を散布し、また下部より水を含む珪フッ
化水素酸の蒸気を導入し、濃硫酸と接触させて塔頂部よ
り、ＳｉＦ４ガスを取り出す構造である。また吸収塔内
部に充填材を充填することや棚段を設けることにより効
率は更に向上する。The absorption tower is a cylindrical reactor shown in FIG.
Concentrated sulfuric acid is sprinkled from the upper part, and hydrosilicofluoric acid vapor containing water is introduced from the lower part, brought into contact with concentrated sulfuric acid, and SiF 4 gas is taken out from the top of the column. Further, the efficiency is further improved by filling the inside of the absorption tower with a packing material or providing a tray.
【００１４】また、流通式の槽型反応器は、図３に示す
ジャッケット付反応槽で、出口にコンデンサーを設置
し、２０℃以下の冷媒を通液にすることにより、発生ガ
ス中のフッ化水素及び水分を抑えることができる。ま
た、図４に示す吸収塔と流通式の縦型反応器を組み合わ
せることも好適な方法である。Further, the flow-through type tank reactor is a reaction tank with a jacket shown in FIG. 3, in which a condenser is installed at the outlet and a refrigerant at 20 ° C. or less is passed through to allow the fluorination in the generated gas. Hydrogen and water can be suppressed. It is also a preferable method to combine the absorption tower shown in FIG. 4 with a flow type vertical reactor.
【００１５】本発明で使用する濃硫酸とは、濃度が８５
重量％以上のものをいい、好ましくは９５重量％以上の
濃硫酸を使用する。この濃硫酸に水を含む珪フッ化水素
酸を接触するので、液相の硫酸の濃度は、幾分低下する
が、８２重量％以上に保つことによって収率よくＳｉＦ
４を回収することができる。また、液相の硫酸の濃度が
７５重量％以下になると、分解が進行せずＳｉＦ４の発
生がなく好ましくない。The concentrated sulfuric acid used in the present invention has a concentration of 85.
A weight percent or more is used, and preferably 95 weight% or more concentrated sulfuric acid is used. Since hydrosilicofluoric acid containing water is brought into contact with this concentrated sulfuric acid, the concentration of sulfuric acid in the liquid phase is somewhat lowered, but by maintaining the concentration of 82% by weight or more, the yield of SiF can be improved.
4 can be recovered. Further, when the concentration of sulfuric acid in the liquid phase is 75% by weight or less, decomposition does not proceed and SiF 4 is not generated, which is not preferable.
【００１６】反応器より発生したＳｉＦ４ガス中には、
若干の水分、フッ化水素等の不純物を含んでいるので、
必要に応じて（深冷分離）蒸留や吸着剤を用い、これら
の不純物を除去することにより、高純度のＳｉＦ４を得
ることができる。吸着剤を用い精製を行う場合、吸着剤
としては活性アルミナ、シリカ、天然または合成ゼオラ
イト、活性炭等が用いられる。In the SiF 4 gas generated from the reactor,
Since it contains some water and impurities such as hydrogen fluoride,
High-purity SiF 4 can be obtained by removing these impurities using distillation (advanced separation) or an adsorbent as needed. When purification is performed using an adsorbent, activated alumina, silica, natural or synthetic zeolite, activated carbon or the like is used as the adsorbent.
【００１７】[0017]
【実施例】以下、本発明を実施例をもって説明する。な
お、％は特記しないかぎり重量％を表す。
実施例１
南アフリカ産燐鉱石を主成分であるＣａ１０（ＰＯ４）
６Ｆ２ベースで５００ｔ／Ｄａｙを主原料とし、これに
硫酸を９８％換算で４９６ｔ／Ｄａｙ 水５２０ｔ／Ｄ
ａｙ、酸化ケイ素を９．９ｔ／Ｄａｙを反応槽で混合
し、石膏及び珪フッ化水素酸を含む４０％粗燐酸液を得
た。該粗燐酸液を濃縮工程に導き、エバポレーターにて
缶液温度８０℃、圧力１００ｔｏｒｒの条件で燐酸濃度
を７５％まで濃縮した。ここで発生した蒸気は、おおよ
そ水分が３００ｔ／Ｄａｙ、珪フッ化水素酸２４ｔ／Ｄ
ａｙであった。次に図２に示す吸収塔（０．４ｍφ×５
ｍ）を用い、フィード管１より該蒸気の一部２ｔ／Ｄａ
ｙを導入した。同時に濃硫酸フィード管３より９８％硫
酸を２０ｔ／Ｄａｙで散布し、塔頂のガス出口管２より
ＳｉＦ４ガス１００ｋｇ／Ｄａｙを回収した。濃硫酸が
珪フッ化水素酸と接触後、フッ化水素及び水分を含むお
よそ９０％濃度の硫酸を液相出口管４より抜液し、燐鉱
石と硫酸液を接触させる初期工程に戻し、粗燐酸を得る
ための硫酸として再使用した。EXAMPLES The present invention will be described below with reference to examples. In addition,% represents weight% unless otherwise specified. Example 1 Ca 10 (PO 4 ) whose main component is South African phosphate rock
6 F 2 based on 500 t / Day as the main raw material, sulfuric acid was added to this as 496 t / Day water 520 t / D
Ay and silicon oxide were mixed in a reaction tank at 9.9 t / Day to obtain a 40% crude phosphoric acid solution containing gypsum and hydrosilicofluoric acid. The crude phosphoric acid solution was introduced into a concentration step, and the phosphoric acid concentration was concentrated to 75% by an evaporator under the conditions of a can temperature of 80 ° C. and a pressure of 100 torr. The steam generated here has a water content of approximately 300 t / Day and hydrosilicofluoric acid of 24 t / D.
It was ay. Next, the absorption tower (0.4 mφ × 5
m), a part of the vapor from the feed pipe 1 is 2 t / Da
introduced y. At the same time, 98% sulfuric acid was sprayed from the concentrated sulfuric acid feed pipe 3 at 20 t / Day, and 100 kg / Day of SiF 4 gas was recovered from the gas outlet pipe 2 at the top of the tower. After the concentrated sulfuric acid comes into contact with hydrosilicofluoric acid, about 90% concentration of sulfuric acid containing hydrogen fluoride and water is drained from the liquid phase outlet pipe 4 and returned to the initial step of bringing the phosphate rock and the sulfuric acid solution into contact with each other. It was reused as sulfuric acid to obtain phosphoric acid.
【００１８】実施例２
実施例１と同様の原料組成で粗燐酸を製造し、濃縮工程
に導いた。ここでも同条件で濃縮し、ここで発生する蒸
気の一部を冷却し凝縮させた。図３に示す流通型反応槽
（容積１００Ｌ）を用い、凝集した珪フッ化水素酸水溶
液２ｔ／Ｄａｙをフィード管１より添加した。同時に濃
硫酸フィード管３より９８％硫酸を２０ｔ／Ｄａｙで供
給し、攪拌機９で混合した。また反応槽のジャケット部
及びコンデンサ−部に５℃の冷却水を循環し、反応熱の
除熱並びにガスに同伴する水分を除去した。この時の液
相の温度は２５℃であった。この方法により、ガス出口
管２よりＳｉＦ４ガス１００ｋｇ／Ｄａｙを回収した。
液相は、液相出口管４より抜液し、燐鉱石と硫酸液を接
触させる初期工程に戻し、粗燐酸を得るための硫酸とし
て再使用した。Example 2 Crude phosphoric acid was produced with the same raw material composition as in Example 1 and led to the concentration step. Here again, it was concentrated under the same conditions, and part of the vapor generated here was cooled and condensed. Using the flow-type reaction tank (volume: 100 L) shown in FIG. 3, 2 t / Day of agglomerated hydrofluoric silicic acid solution was added from the feed pipe 1. At the same time, 98% sulfuric acid was supplied from the concentrated sulfuric acid feed pipe 3 at 20 t / Day and mixed by the stirrer 9. Further, cooling water at 5 ° C. was circulated in the jacket section and the condenser section of the reaction tank to remove the heat of reaction and to remove water accompanying gas. The temperature of the liquid phase at this time was 25 ° C. By this method, 100 kg / Day of SiF 4 gas was recovered from the gas outlet pipe 2.
The liquid phase was drained from the liquid phase outlet pipe 4, returned to the initial step of contacting the phosphate rock with the sulfuric acid solution, and reused as sulfuric acid for obtaining crude phosphoric acid.
【００１９】[0019]
【発明の効果】本発明は、燐酸製造プロセスから珪フッ
化水素酸を副生させ、これに濃硫酸を接触させてＳｉＦ
４を回収する方法である。また本発明は、燐鉱石中のフ
ッ素の利用法の一つとして、連続プロセスを実用化し、
コストの低減を図るものである。According to the present invention, hydrosilicofluoric acid is produced as a by-product from the phosphoric acid production process, and concentrated sulfuric acid is brought into contact with this to produce SiF.
It is a method of collecting 4 . The present invention also puts a continuous process into practical use as one of the methods of utilizing fluorine in phosphate rock.
It is intended to reduce the cost.
【００２０】[0020]
【図１】 本発明工程図の一例FIG. 1 is an example of a process chart of the present invention
【図２】 吸収塔[Figure 2] Absorption tower
【図３】 流通式槽型反応器FIG. 3 Flow-through tank reactor
【図４】 吸収塔と流通式槽型を組み合わせた反応器の
一例FIG. 4 An example of a reactor in which an absorption tower and a flow tank type are combined
１．水分を含む珪フッ化水素酸のフィード管 ２．ガス出口管 ３．濃硫酸フィード管 ４．液相出口管 ５．吸収塔本体 ６．冷媒循環用配管 ７．流通式槽型反応器本体 ８．コンデンサー ９．攪拌機 １０．バルブ 1. Feed tube for hydrosilicofluoric acid containing water 2. Gas outlet pipe 3. Concentrated sulfuric acid feed tube 4. Liquid phase outlet pipe 5. Absorption tower body 6. Refrigerant circulation piping 7. Flow tank type reactor body 8. condenser 9. Stirrer 10. valve
Claims (2)
するプロセスにおいて、該燐鉱石と該硫酸液を接触する
際に酸化ケイ素を加え、得られた粗燐酸を濃縮し、発生
する蒸気あるいは凝縮液中の珪フッ化水素酸を濃硫酸に
て分解し、フッ化ケイ素を得ることを特徴とする燐酸製
造プロセスからフッ化ケイ素を回収する方法。1. In a process for producing phosphoric acid by contacting a phosphate rock with a sulfuric acid solution, silicon oxide is added at the time of contacting the phosphate rock with the sulfuric acid solution, and the obtained crude phosphoric acid is concentrated to generate steam or A method for recovering silicon fluoride from a phosphoric acid production process, characterized in that hydrosilicofluoric acid in a condensate is decomposed with concentrated sulfuric acid to obtain silicon fluoride.
後、フッ化水素及び水分を含む硫酸を、燐鉱石と硫酸液
を接触させる初期工程に戻し、粗燐酸を得るための硫酸
として再使用する請求項１記載の方法。2. After decomposing hydrofluoric silicic acid with concentrated sulfuric acid, sulfuric acid containing hydrogen fluoride and water is returned to the initial step of contacting phosphate rock with a sulfuric acid solution to obtain crude phosphoric acid as sulfuric acid. The method according to claim 1, wherein the method is reused.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24289196A JP3449675B2 (en) | 1996-09-13 | 1996-09-13 | Method for recovering silicon fluoride from phosphoric acid production process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24289196A JP3449675B2 (en) | 1996-09-13 | 1996-09-13 | Method for recovering silicon fluoride from phosphoric acid production process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1087314A JPH1087314A (en) | 1998-04-07 |
| JP3449675B2 true JP3449675B2 (en) | 2003-09-22 |
Family
ID=17095769
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24289196A Expired - Lifetime JP3449675B2 (en) | 1996-09-13 | 1996-09-13 | Method for recovering silicon fluoride from phosphoric acid production process |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3449675B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110723860A (en) * | 2019-11-28 | 2020-01-24 | 四川恒泽建材有限公司 | Waste water treatment device for accelerator |
-
1996
- 1996-09-13 JP JP24289196A patent/JP3449675B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1087314A (en) | 1998-04-07 |
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