JP2963905B2 - Method for producing high-purity metal fluoride - Google Patents
Method for producing high-purity metal fluorideInfo
- Publication number
- JP2963905B2 JP2963905B2 JP14437890A JP14437890A JP2963905B2 JP 2963905 B2 JP2963905 B2 JP 2963905B2 JP 14437890 A JP14437890 A JP 14437890A JP 14437890 A JP14437890 A JP 14437890A JP 2963905 B2 JP2963905 B2 JP 2963905B2
- Authority
- JP
- Japan
- Prior art keywords
- fluoride
- precipitate
- impurities
- aqueous solution
- purity metal
- 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
Landscapes
- Glass Compositions (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Description
【発明の詳細な説明】 （発明の属する技術分野） 本発明は高純度金属フッ化物の製造方法、更に詳細に
はフッ化物光ファイバ用高純度フッ化物原料の製造方法
に関するものである。Description: TECHNICAL FIELD The present invention relates to a method for producing a high-purity metal fluoride, and more particularly to a method for producing a high-purity fluoride raw material for a fluoride optical fiber.
（従来の技術および問題点） フッ化物光ファイバは石英系を凌ぐ10-2dB/km以下の
伝送損失が期待されており、長距離無中継が可能な伝送
媒体として有望視されている。しかし、これまで報告さ
れているフッ化物光ファイバの伝送値は1dB/km前後であ
る。フッ化物光ファイバの超低損失化を阻害する要因と
してCr、Fe、Co、Ni、Cuなどの遷移金属不純物による吸
収損失および酸素不純物による散乱損失がある。これら
の不純物は出発フッ化物原料から来るものが最も多いと
考えられるため、遷移金属不純物、酸素不純物を含まな
い高純度フッ化物原料の作製が強く望まれている。(Conventional technology and problems) Fluoride optical fiber is expected to have a transmission loss of 10 -2 dB / km or less, which is superior to that of silica-based fiber, and is regarded as a promising transmission medium capable of long-distance non-repeating. However, the transmission values of fluoride optical fibers reported so far are around 1 dB / km. Factors that hinder ultra-low-loss fluoride optical fibers include absorption loss due to transition metal impurities such as Cr, Fe, Co, Ni, and Cu and scattering loss due to oxygen impurities. Since it is considered that most of these impurities come from the starting fluoride raw material, it is strongly desired to produce a high-purity fluoride raw material containing no transition metal impurities and oxygen impurities.
光ファイバ用フッ化物ガラス組成にはZrF4系が主に使
われており、その主成分はZrF4、AlF3、LaF3などの網目
形成（４価、３価）フッ化物と、BaF2、NaFなどのアル
カリ土類（２価）、アルカリ金属（１価）フッ化物であ
る。ZrF 4 is mainly used in the composition of fluoride glass for optical fiber, and the main components are ZrF 4 , AlF 3 , LaF 3 and other network-forming (tetravalent, trivalent) fluorides, BaF 2 , These are alkaline earth (divalent) and alkali metal (monovalent) fluorides such as NaF.
従来のフッ化物精製法には昇華法や気相反応法などの
乾式精製法と溶媒抽出やイオン交換による湿式精製法が
あった。昇華精製法はZrF4、AlF3などには適用可能であ
り、遷移金属および酸化物の除去が同時に行われる。Conventional fluoride purification methods include a dry purification method such as a sublimation method and a gas phase reaction method, and a wet purification method by solvent extraction or ion exchange. The sublimation purification method is applicable to ZrF 4 , AlF 3, and the like, and the transition metal and the oxide are simultaneously removed.
しかし、BaF2については昇華精製では遷移金属は揮発
除去できるが、BaF2の蒸気圧が低いため高温で昇華精製
すると酸化物が残存し、光ファイバ原料としては適さな
いという欠点があった。However, BaF 2 has a drawback that transition metals can be volatilized and removed by sublimation purification, but oxides remain after sublimation purification at high temperature due to the low vapor pressure of BaF 2 , which is not suitable as an optical fiber material.
アルカリ土類金属、アルカリ金属中の遷移金属不純物
除去に関しては湿式精製法が知られているが、水溶液の
フッ素化処理および乾燥において、水酸基の残留、最終
的には酸素不純物の残留があり、フッ化物光ファイバ用
原料としては適さないと考えられていた。例えば、Ba
（NO3)2、Na2CO3水溶液を用いて湿式精製した後、フッ
素化して作製した沈殿物には陰イオンの共沈によるN
O3 -、CO3 2-の混入が確認された。さらに、HFとH2Oを含
む沈殿物を乾燥するため、HFの離脱と共にOH基の脱水縮
合反応が進行し、最終的に酸素不純物の残留がある。Ba
Cl2水溶液を用いた場合は、フッ素化工程でBaClFが生成
・沈殿し、BaF2は得られない。For the removal of alkaline earth metals and transition metal impurities in alkali metals, a wet purification method is known. However, in the fluorination treatment and drying of an aqueous solution, residual hydroxyl groups and finally oxygen impurities remain. It was considered unsuitable as a raw material for a compound optical fiber. For example, Ba
(NO 3 ) 2 , after wet purification using an aqueous solution of Na 2 CO 3 , and then fluorinated to produce a precipitate.
O 3 -, CO 3 incorporation of 2 was confirmed. Furthermore, since the precipitate containing HF and H 2 O is dried, the dehydration-condensation reaction of the OH group proceeds with the elimination of HF, and finally oxygen impurities remain. Ba
When a Cl 2 aqueous solution is used, BaClF is generated and precipitated in the fluorination step, and BaF 2 cannot be obtained.
BaClFをさらに水分存在下でF2ガス処理し、BaF2・HF
を作製する方法（文献:F.Chatelut,C.Eyraud,Bull.Soc.
Chim.,（1973）p.2646〜）が提案されているが、F2処理
操作の危険性およびBaF2・HF作製工程の複雑さが欠点に
挙げられる。BaClF is further treated with F 2 gas in the presence of moisture, and BaF 2
(Literature: F. Chatelut, C. Eyraud, Bull. Soc.
Chim., (1973) p.2646~) but has been proposed, the complexity of the risk of F 2 processing operations and BaF 2 · HF manufacturing steps mentioned drawbacks.
（発明の目的） 本発明の目的は、高純度金属フッ化物の製造におい
て、湿式精製法を適用して遷移金属不純物を低減し、か
つ酸化物不純物の低減を可能とするもので、光ファイバ
用高純度金属フッ化物を提供することにある。(Object of the Invention) An object of the present invention is to reduce transition metal impurities and to reduce oxide impurities by applying a wet purification method in the production of high-purity metal fluorides. It is to provide a high-purity metal fluoride.
（問題点を解決するための手段） 上記問題点を解決するため、本発明による高純度金属
フッ化物の製造方法は、高純度金属フッ化物を製造する
方法において、当該金属の酢酸塩水溶液の状態で湿式精
製し、その後、フッ素化剤を用いて沈殿を作製し、当該
沈殿を脱水、乾燥することを特徴とする。(Means for Solving the Problems) In order to solve the above problems, a method for producing a high-purity metal fluoride according to the present invention comprises the steps of: , And thereafter, a precipitate is prepared using a fluorinating agent, and the precipitate is dehydrated and dried.
本発明は湿式精製による遷移金属不純物除去の長所を
活かしつつ、酢酸塩水溶液の状態から酸性フッ化物とし
て沈殿させることを最も主要な特徴とする。従来の技術
では、塩化物、硝酸塩、炭酸塩などの水溶液を用いてい
たため、陰イオンの共沈現象、生成酸性フッ化物沈殿中
の吸着水などがあったが、酢酸塩ではこれらの現象が見
られない点が異なる。従って、得られる高純度金属フッ
化物は酸素不純物が大幅に低減されるという特徴があ
る。The most important feature of the present invention is to precipitate an acidic aqueous solution from an aqueous acetate solution while taking advantage of the removal of transition metal impurities by wet purification. In the conventional technology, an aqueous solution of chloride, nitrate, carbonate, etc. was used, so there were co-precipitation phenomena of anions and adsorbed water during precipitation of generated acid fluoride. These phenomena were observed in acetate. Is different. Therefore, the obtained high-purity metal fluoride is characterized in that oxygen impurities are greatly reduced.
本発明によれば、まず製造する金属フッ化物の前記金
属の酢酸塩水溶液の状態で湿式精製する。このような金
属としては、例えばアルキル金属およびアルキル土類金
属などを例としてあげることができる。According to the present invention, the metal fluoride to be produced is first subjected to wet purification in the state of an aqueous solution of the metal acetate. Examples of such a metal include an alkyl metal and an alkyl earth metal.
この湿式精製の方法は、本発明において基本的に限定
されるものではなく、たとえば溶媒抽出などの方法で、
Cr、Fe、Co、Ni、Cuなどの遷移金属不純物などを除去し
てもよく、イオン交換法によって不純物を除去してもよ
い。The method of this wet purification is not basically limited in the present invention, for example, by a method such as solvent extraction,
Transition metal impurities such as Cr, Fe, Co, Ni, and Cu may be removed, or the impurities may be removed by an ion exchange method.
上述のように湿式精製した後、フッ素化剤を添加し、
フッ化物沈殿を生じしめる。このフッ素化剤は、本発明
において基本的に限定されるものではなく、金属フッ化
物沈殿を生じしめるものであれば基本的にいかなるもの
でもよい。たとえばフッ化水素酸、フッ化アンモニウム
水溶液、フッ化水素ガスのいずれか１つ、または２つ以
上の混合物であることができる。After wet purification as described above, add a fluorinating agent,
This causes fluoride precipitation. The fluorinating agent is not fundamentally limited in the present invention, and may be basically any one that causes metal fluoride precipitation. For example, it may be any one of hydrofluoric acid, an aqueous solution of ammonium fluoride, and hydrogen fluoride gas, or a mixture of two or more thereof.
このようにフッ素化剤によって沈殿を生じしめた後、
前記沈殿を脱水、乾燥させる。脱水、感想工程は、本発
明において基本的に限定されるものではない。例えば、
真空雰囲気、不活性雰囲気で行なうことができる。After causing precipitation by the fluorinating agent,
The precipitate is dehydrated and dried. The dehydration and impression steps are not basically limited in the present invention. For example,
It can be performed in a vacuum atmosphere or an inert atmosphere.
以下、実施例によって本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail with reference to examples.
（実施例１） Ba（CH3COO)2塩を出発とするBaF2の製造方法について
以下に説明する。(Example 1) Ba (CH 3 COO) 2 salt is described below a method for manufacturing the BaF 2 used as the starting.
Ba（CH3COO)2を秤量後純水に溶解し、溶媒抽出により
Cr、Fe、Co、Ni、Cuの遷移金属不純物を抽出精製した
後、フッ素化剤としてフッ化水素酸を加え、フッ化物沈
殿とする。フッ化物沈殿は希フッ化水素酸で洗浄後、室
温にて真空脱水乾燥を行った。得られた乾燥物の電子顕
微鏡写真から結晶小面のはっきりした単結晶であり、Ba
（NO3)2水溶液からの沈殿乾燥物が針状であることと大
きく異なっている。さらに、第１図は真空乾燥後のフッ
化物のDTA−TG曲線であり、120℃から減量し、235℃で
完了し、重量減少率は10.2％である。DTA曲線は223℃、
1353℃に吸熱ピークがある。232℃の吸熱ピークはHF離
脱に伴う単一ピークであり、脱水縮合による吸熱ピーク
は見られない。1353℃の吸熱ピークはBaF2の融点に相当
するものである。Ba (CH 3 COO) 2 is weighed and dissolved in pure water.
After extracting and purifying transition metal impurities of Cr, Fe, Co, Ni, and Cu, hydrofluoric acid is added as a fluorinating agent to form a fluoride precipitate. The fluoride precipitate was washed with dilute hydrofluoric acid and then vacuum-dehydrated and dried at room temperature. From the electron micrograph of the obtained dried product, it is a single crystal with clear crystal facets, and Ba
This is significantly different from the fact that the dried precipitate from the (NO 3 ) 2 aqueous solution is acicular. FIG. 1 is a DTA-TG curve of the fluoride after vacuum drying. The weight was reduced from 120 ° C. and completed at 235 ° C., and the weight loss was 10.2%. DTA curve is 223 ° C,
There is an endothermic peak at 1353 ° C. The endothermic peak at 232 ° C. is a single peak associated with HF elimination, and no endothermic peak due to dehydration condensation is observed. The endothermic peak at 1353 ° C. corresponds to the melting point of BaF 2 .
真空乾燥後のフッ化物はBaF2・HFであることをＸ線回
折で確認した。また、前記フッ化物を400℃で真空乾燥
し、これについてＸ線回折を行い、立方晶のBaF2が作製
されていることを確認した。第１表は本発明で製造した
BaF2の中性子放射化分析による遷移金属不純物、荷電粒
子放射化分析による酸素不純物の定量結果であり、酸素
1ppm未満、クロム、鉄、コバルト、ニッケル、銅いずれ
も1ppb未満の値が得られた。放射化分析によるフッ化物
の酸素の検出下限は1ppmであり、酸素不純物について検
出下限値まで高純度化できている。It was confirmed by X-ray diffraction that the fluoride after vacuum drying was BaF 2 .HF. Further, the fluoride was vacuum-dried at 400 ° C. and subjected to X-ray diffraction to confirm that cubic BaF 2 was produced. Table 1 was prepared according to the invention
This is a quantitative result of transition metal impurities by neutron activation analysis of BaF 2 and oxygen impurities by charged particle activation analysis.
Values of less than 1 ppm and less than 1 ppb for all of chromium, iron, cobalt, nickel and copper were obtained. The lower limit of detection of oxygen in fluoride by activation analysis is 1 ppm, and oxygen impurities can be highly purified to the lower limit of detection.
本発明で作製したBaF2をフッ化物光ファイバ原料成分
として使用し、その効果としては散乱損失の小さい良好
な光ファイバが製造できた。真空乾燥後のBaF2・HFを原
料に使用しても同様に良好な光ファイバが製造できた。Using BaF 2 produced in the present invention as a raw material component of a fluoride optical fiber, an advantageous effect was that an excellent optical fiber having a small scattering loss could be produced. Even if BaF 2 HF after vacuum drying was used as a raw material, similarly good optical fibers could be produced.
フッ素化剤にフッ化アンモニウム水溶液を使用してフ
ッ化物沈殿を作製しても、前記と同様にBaF2・HFが製造
できた。BaF 2 .HF was produced in the same manner as described above even when a fluoride precipitate was prepared using an aqueous solution of ammonium fluoride as the fluorinating agent.
（実施例２） Na（CH3COO）塩を出発とするNaFの製造方法について
以下に説明する。 Example 2 A method for producing NaF starting from a Na (CH 3 COO) salt will be described below.
Na（CH3COO）塩を溶解後水溶液とし、溶媒抽出精製に
より遷移金属不純物を除去後、フッ素化剤としてフッ化
水素ガスを水溶液内にバブルさせを、フッ化物沈殿とす
る。フッ化物沈殿はAr乾燥ガス気流で乾燥させたものに
ついてDTA−TGおよび赤外吸収スペクトル測定を行っ
た。第２図は前記乾燥物の赤外吸収スペクトルであり、
2100cm-1、1500〜1700cm-1、1210cm-1にHF2 -に相当する
吸収ピークがあった。また、前記乾燥物のDTA−TGは第
１図のDTAの第１番目の吸熱ピークと同様に単一ピーク
であり、脱水縮合は見られず、Ｘ線回折結果からNaF・H
Fであることが確認された。さらに、Ar乾燥ガス気流中4
00℃まで加熱し、加熱後のものについてＸ線回折を行
い、NaFであることを確認した。NaF・HFおよびNaFにつ
いて遷移金属不純物分析、酸素不純物分析を行い、第１
表に示したと同様、NaF・HF、NaFの両方についてCr、F
e、Co、Ni、Cuは各々1ppb以下、酸素は1ppm以下とな
り、NaF・HFと同様HFを除去したNaFについても酸素不純
物分析結果に示すように酸素を減少させる効果があっ
た。After dissolving Na (CH 3 COO) salt to form an aqueous solution, and removing transition metal impurities by solvent extraction purification, hydrogen fluoride gas as a fluorinating agent is bubbled into the aqueous solution to form a fluoride precipitate. DTA-TG and infrared absorption spectrum measurement were performed on the fluoride precipitate dried with an Ar dry gas stream. FIG. 2 is an infrared absorption spectrum of the dried product,
There was an absorption peak corresponding to - 2100cm -1, 1500~1700cm -1, HF 2 to 1210cm -1. Further, DTA-TG of the dried product was a single peak similarly to the first endothermic peak of DTA in FIG. 1, no dehydration condensation was observed, and NaF.H
F was confirmed. In addition, Ar dry gas stream 4
After heating to 00 ° C., X-ray diffraction was performed on the sample after heating to confirm that it was NaF. Transition metal impurity analysis and oxygen impurity analysis were performed for NaF / HF and NaF.
As shown in the table, for both NaFHF and NaF, Cr, F
Each of e, Co, Ni, and Cu was 1 ppb or less, and oxygen was 1 ppm or less. Like NaF.HF, NaF from which HF was removed had an effect of reducing oxygen as shown in the oxygen impurity analysis results.
本発明で作製したNaF・HFあるいはNaFをフッ化物光フ
ァイバ原料成分として使用し、その効果としては散乱損
失の小さい良好な光ファイバが製造できた。By using NaF.HF or NaF produced in the present invention as a raw material component of a fluoride optical fiber, an advantageous optical fiber having a small scattering loss was produced.
（実施例３） Li（CH3COO）塩を出発とするLiFの製造方法について
以下に説明する。Example 3 A method for producing LiF starting from a Li (CH 3 COO) salt will be described below.
Li（CH3COO）塩の水溶液中の遷移金属不純物をイオン
交換法により精製除去した後、フッ素化剤としてフッ化
水素酸を加えフッ化物沈殿とする。フッ化物沈殿物は、
希フッ化水素酸で洗浄後、120℃で真空脱水乾燥を行っ
た。乾燥物についてＸ線回折を行いLiFであることを確
認した。本発明で作製したLiFについて酸素不純物、遷
移金属不純物を分析し、分析結果は第１表と同じく、酸
素は1ppm以下、Cr、Fe、Co、Ni、Cuは各々1ppb以下とな
り、実施例２で示したNaF・HF、HFと同様に酸素を減少
させる効果があった。After purifying and removing transition metal impurities in an aqueous solution of Li (CH 3 COO) salt by an ion exchange method, hydrofluoric acid is added as a fluorinating agent to form a fluoride precipitate. The fluoride precipitate
After washing with dilute hydrofluoric acid, vacuum dehydration and drying were performed at 120 ° C. X-ray diffraction of the dried product confirmed that it was LiF. Oxygen impurities and transition metal impurities were analyzed for LiF produced in the present invention, and the analysis results were the same as in Table 1, oxygen was 1 ppm or less, and Cr, Fe, Co, Ni, and Cu were each 1 ppb or less. It had the effect of reducing oxygen in the same way as the NaF.HF and HF shown.
本発明で作製したLiFをフッ化物光ファイバ原料成分
として使用し、その効果としては散乱損失の小さい良好
な光ファイバが製造できた。Using LiF produced in the present invention as a raw material component of a fluoride optical fiber, an advantageous effect was that an excellent optical fiber with small scattering loss was produced.
（発明の効果） 以上説明したように、本発明による高純度金属フッ化
物の製造方法は、湿式精製法による超高純度化とあわせ
て酸素不純物の除去が行えるため、遷移金属不純物、酸
素不純物の両方が少ない高純度フッ化物が得られる。こ
れをフッ化物光ファイバ原料として用いることにより超
低損失のフッ化物光ファイバを製造できる利点がある。(Effects of the Invention) As described above, the method for producing a high-purity metal fluoride according to the present invention can remove oxygen impurities together with ultra-high purification by a wet purification method. A high-purity fluoride in which both are small is obtained. By using this as a raw material of a fluoride optical fiber, there is an advantage that an ultra low loss fluoride optical fiber can be manufactured.
第１図は真空乾燥後のBa−フッ化物のDTA−TG曲線、第
２図はArガスで乾燥したNa-フッ化物の赤外吸収スペク
トルである。 １……DTA曲線、２……TG曲線。FIG. 1 is a DTA-TG curve of Ba-fluoride after vacuum drying, and FIG. 2 is an infrared absorption spectrum of Na - fluoride dried with Ar gas. 1 ... DTA curve, 2 ... TG curve.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) C01B 9/08 C01F 11/22 C01D 3/02 C01D 15/04 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. 6 , DB name) C01B 9/08 C01F 11/22 C01D 3/02 C01D 15/04
Claims (2)
て、当該金属の酢酸塩水溶液の状態で湿式精製し、その
後、フッ素化剤を用いて沈殿を作製し、当該沈殿を脱
水、乾燥することを特徴とする高純度金属フッ化物の製
造方法。In a method for producing a high-purity metal fluoride, wet purification is performed in the form of an aqueous solution of an acetate of the metal, and thereafter, a precipitate is prepared using a fluorinating agent, and the precipitate is dehydrated and dried. A method for producing a high-purity metal fluoride, comprising:
水素酸、フッ化アンモニウム水溶液、フッ化水素ガスの
いずれか１つ、または２つ以上の混合物であることを特
徴とする特許請求の範囲第１項記載の高純度金属フッ化
物の製造方法。2. The method according to claim 1, wherein the fluorinating agent in the step of preparing the precipitate is at least one of hydrofluoric acid, an aqueous solution of ammonium fluoride, and hydrogen fluoride gas, or a mixture of two or more thereof. 2. The method for producing a high-purity metal fluoride according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14437890A JP2963905B2 (en) | 1990-06-04 | 1990-06-04 | Method for producing high-purity metal fluoride |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14437890A JP2963905B2 (en) | 1990-06-04 | 1990-06-04 | Method for producing high-purity metal fluoride |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0442802A JPH0442802A (en) | 1992-02-13 |
| JP2963905B2 true JP2963905B2 (en) | 1999-10-18 |
Family
ID=15360735
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14437890A Expired - Lifetime JP2963905B2 (en) | 1990-06-04 | 1990-06-04 | Method for producing high-purity metal fluoride |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2963905B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2727103B1 (en) * | 1994-11-23 | 1996-12-27 | Kodak Pathe | PROCESS FOR THE PREPARATION OF METAL HALIDES BY SOL-GEL ROUTE |
| JP5318437B2 (en) * | 2008-03-12 | 2013-10-16 | ステラケミファ株式会社 | Method for purifying metal fluorides |
| US8583326B2 (en) * | 2010-02-09 | 2013-11-12 | Agjunction Llc | GNSS contour guidance path selection |
| CN101967003B (en) * | 2010-10-25 | 2012-07-04 | 宁波诺尔丽化学科技有限公司 | Method for preparing barium fluoride from organic fluoridation waste |
| CN113307296B (en) * | 2021-06-17 | 2023-08-18 | 秦皇岛微晶科技有限公司 | Preparation method of barium fluoride with low oxygen content |
-
1990
- 1990-06-04 JP JP14437890A patent/JP2963905B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0442802A (en) | 1992-02-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Fletcher et al. | Nitrato and nitro complexes of nitrosylruthenium | |
| JP6521404B2 (en) | Hydrogen-containing rare earth fluoride, method for producing the same and use thereof | |
| JPH037608B2 (en) | ||
| JP2963905B2 (en) | Method for producing high-purity metal fluoride | |
| JP2772302B2 (en) | Method for producing high-purity metal fluoride | |
| JPS63239128A (en) | Production of uranium oxide | |
| US4812302A (en) | Process for preparing high purity Mn3 O4 | |
| KR100360559B1 (en) | Process for the production of extra fine powder of Cobalt | |
| CA1122416A (en) | Method of extracting columbium-tantalum values from pyrochlore ores | |
| US3007770A (en) | Extraction of lithium | |
| JP4414048B2 (en) | Method for producing vanadium (III) oxide | |
| JP3673380B2 (en) | Method for producing high purity tellurium dioxide | |
| JPH0327390A (en) | Manufacture of high purity copper alkoxido | |
| US3642440A (en) | Process for nickel-cobalt separation | |
| JPH06239604A (en) | Production of high-purity metal fluoride | |
| JPH0742103B2 (en) | Method for producing alkali metal fluoride | |
| JP3594102B2 (en) | Method for producing indium fluoride complex salt | |
| JP3412334B2 (en) | Method for producing high purity metal fluoride | |
| JP3591746B2 (en) | Method for producing zinc fluoride | |
| Harmon et al. | Conversion chemistry of plutonium nitrate | |
| JP3577224B2 (en) | Method for producing strontium hydrogen fluoride | |
| JPH0617207B2 (en) | Method for producing high-purity metal fluoride | |
| JP3847635B2 (en) | Method for producing magnesium carbonate powder | |
| CN110642253B (en) | Preparation method for preparing nano reduced silicon through aluminothermic reaction | |
| JPH06271314A (en) | Production of high purity barium halide |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 8 Free format text: PAYMENT UNTIL: 20070813 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 9 Free format text: PAYMENT UNTIL: 20080813 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080813 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 10 Free format text: PAYMENT UNTIL: 20090813 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090813 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100813 Year of fee payment: 11 |
|
| EXPY | Cancellation because of completion of term |