JPH06271314A - Production of high purity barium halide - Google Patents

Abstract

PURPOSE:To produce high purity barium halide useful for manufacturing optical fiber having a high amplification factor by extracting and removing transition metal impurities from a barium aqueous solution with a dithiocarbamate thereafter preparing barium halide from the resulting solution. CONSTITUTION:After adjusting the pH of the barium aq. solution, the transition metal impurites are extracted and removed from the barium aq. solution by adding a dithiocarbamate represented by the formula RCS2R1 to the solution. The objective high purity barium halide is produced by preparing barium halide from the barium aq. solution, from which the transition metal impurites are extracted and removed. In the above formula, R is (C2H5)2N-, etc.; R1 is H<+>, NH4<+>, NH2<+>(C2H5)2 or Na<+>. This production features in which the barium halide, such as barium chloride, barium fluoride, etc., is produced from a water-soluble barium salt such as barium nitrate, acetate, chloride, etc., or barium hydroxide as the starting material, differnetly from the conventional methods using water- insoluble barium carbonate as the starting material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-purity barium halide, and more particularly to a method for producing a high-purity raw material for optical fibers for optical amplification.

[0002]

_2. Description of the Related Art BaF ₂ is ZrF ₄ , LaF ₃ , Al.
It is a constituent raw material of an optical fiber for optical amplification together with F ₃ and NaF. Of these, a part of the composition of BaF ₂ is replaced with barium chloride, that is, BaCl ₂ or barium fluorinated chloride, that is, BaFCl, to improve amplification. Factors that hinder the amplification efficiency of the optical fiber for optical amplification include transition metals such as chromium, iron, cobalt, nickel and copper mixed in the optical fiber. These transition metals exist as impurities in the constituent raw materials, and in order to realize an optical fiber for optical amplification using a fluoride optical fiber, the production of metal fluoride containing no transition metal is mainly used for the sublimation of the dry purification method. Purification of metal fluorides (M. Robinson, Mat. Sc.
i. Forum, 5, 19 (1985)). On the other hand, the conventional production of high-purity barium chloride and barium fluorochloride was performed by dissolving high-purity barium carbonate in hydrochloric acid.
The precipitated barium chloride crystals are dried to obtain barium chloride from barium chloride dihydrate, or there is a method of producing barium fluoride chloride by reacting barium chloride with fluorine gas. It is 1 ppm or more. The conventional method for producing barium chloride or barium fluoride chloride has a problem in that the purity does not include purification in the production process, and therefore depends entirely on the purity of the starting material, resulting in impurity contamination in the subsequent process.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to use an aqueous solution containing barium as a starting material and to remove impurities of transition metals such as chromium, iron, cobalt, nickel and copper contained in the aqueous solution as one organic reagent. It is an object of the present invention to provide a method for solving the above-mentioned drawbacks by solvent extraction using a combination of a solvent and a solvent, and then producing barium halide by a reaction with highly pure hydrochloric acid or a fluorinating agent.

[0004]

In order to solve the above problems, the method for producing barium halide according to the present invention comprises the following general formula: RCS after adjusting the pH of an aqueous barium solution.
_{It is characterized} in that dithiocarbamate composed of ₂ R ₁ is added to extract and remove the impurity transition metal, and barium halide is produced from the barium aqueous solution from which the impurity transition metal is extracted and removed. General formula: RCS ₂ R ₁ (wherein, R represents _{(C 2 H 5) 2 N-} ,
Or

[0005]

[Chemical 2] R ₁ is H ₂ , NH ₄ ⁺ , NH ₂ ⁺ (C ₂ H ₅ ) ₂ ,
Indicates Na ⁺ . )

[0006]

The present invention uses an aqueous solution of barium in order to solve the problems of the prior art method for producing barium chloride starting from barium carbonate and the method for producing barium fluorochloride starting from barium chloride. However, for each of the transition metal impurities present in the aqueous solution, such as chromium, iron, cobalt, nickel, and copper elements, determine the organic reagent and solvent that form the most stable complex, and determine the transition metal impurities in the solvent. The most important feature is to extract and remove,
For example, hydrochloric acid or a fluorinating agent is added to the aqueous barium solution remaining after extraction and removal to form a barium halide hydrate, which is dehydrated and dried to produce high-purity barium chloride or barium fluorochloride. .

The conventional method for producing barium fluorochloride using barium chloride or barium chloride using fluorine gas is that the starting material barium carbonate is not dissolved in an aqueous solution, but nitrates, acetates, chlorides, etc. The difference lies in that barium chloride, barium fluoride chloride, etc. are produced using the water-soluble salt or barium hydroxide as a starting material.

In the present invention, the organic reagent for extraction used is a dithiocarbamate compound. Such organic reagents can be used with organic solvents. As the organic reagent, a dithiocarbamate represented by the general formula: RCS ₂ R ₁ is used. In the above formula, R is (C ₂ H ₅ ) ₂ N
-Or

[0009]

[Chemical 3] And R ₁ is H ⁺ , NH ₄ ⁺ , NH ₂ ⁺ (C ₂
H ₅ ) ₂ or Na ⁺ .

[0010]

【Example】

(Example 1) The optimum extraction conditions for chromium, iron, cobalt and nickel, and copper using barium acetate as a starting material and using an organic reagent will be described below.

Ba (CH ₃ COO) ₂ 100 in a beaker
g Weighed and made into a solution, ⁵¹ Cr, ⁵⁹ Fe, ⁶⁰ CO, ⁶⁵ N
After adding 100 μg of each of the radioisotopes of i and ⁶⁴ Cu, pH is set to 2.0 to 5.0. 100 ml of an organic reagent 0.1 g of diethylammonium diethyldithiocarbamate (hereinafter abbreviated as DDDC) was added to the pH-adjusted solution.
After dissolving it in carbon tetrachloride, add 20 ml of it, transfer to a separating funnel, and shake for 5 minutes. After shaking, 5
The mixture is allowed to stand for a minute, the radioactivity of the organic phase and the aqueous phase is measured with a radiation detector, and the extraction rate of the five elements into the organic phase is calculated. As the extraction rate, a value of 99.9% or more was obtained in the region of pH = 2.0 to 5.0 for the five elements of chromium, iron, cobalt, nickel, and copper.

Barium nitrate and barium chloride (BaC1 ₂ .2H ₂ 0) were used as starting materials, and D
99.9% even when DDC and chloroform extraction are performed
The above extraction rates are obtained in the above pH range. If the above organic reagents and solvents are used, 99.9% or more of chromium,
It shows the effect of extracting iron, cobalt, nickel, and copper, in other words, eliminating these five elements up to three digits.

(Example 2) A method for producing high-purity barium chloride using barium nitrate as a starting material will be described with reference to the process chart of FIG. Barium nitrate 10g, pure water 150m
After dissolving in 1, ammonium acetate was added, pH = 4.0
Set between 5.0. After extracting and removing impurities by using 50 ml of a solution prepared by dissolving 1.0 g of DDDC in 100 ml of carbon tetrachloride, 150 ml of concentrated hydrochloric acid was added to the aqueous phase, heated on a water bath, concentrated and cooled, and the precipitated crystals were filtered by suction. Then, it is washed with a small amount of pure water to obtain barium chloride dihydrate. Barium chloride dihydrate is dehydrated and dried in a vacuum dryer at room temperature to 130 ° C. to produce barium chloride. The chloride dihydrate can also be obtained by performing the above-mentioned extraction operation using barium acetate, barium chloride or barium hydroxide as the starting material. In addition, the activation analysis of chromium, iron, cobalt, nickel, and copper in the prepared barium chloride was performed.
An analysis result of 1 ppb was obtained for the five elements, and barium chloride having a higher purity than the conventional analysis value of the impurity concentration of barium chloride could be produced.

Example 3 Barium acetate (Ba (CH ₃
A method for producing barium chloride using COO) ₂ ) as a starting material will be described with reference to the process chart of FIG. 100 g of barium acetate is dissolved in 150 ml of pure water. A small amount of ammonium acetate is added to the aqueous solution, and the pH is set between 4.0 and 6.0. Sodium diethyldithiocarbamate (hereinafter abbreviated as DDTC) 1.0 g was dissolved in pure water 10 ml, and 1 ml of this and 50 ml of carbon tetrachloride were used to extract and remove impurities. Then, 150 ml of concentrated hydrochloric acid was added to the aqueous phase, and the mixture was placed on a water bath. After heating, concentrating and cooling, the precipitated crystals are suction filtered and washed with a small amount of pure water to obtain barium chloride dihydrate. Barium chloride dihydrate is dehydrated and dried in a vacuum dryer at room temperature to 130 ° C. to produce barium chloride. The chloride dihydrate can also be obtained by performing the above extraction operation using barium nitrate, barium chloride, or barium hydroxide as the starting material. In addition, the activation analysis of chromium, iron, cobalt, nickel, and copper in the prepared barium chloride was performed.
An analysis result of 1 ppb was obtained for the five elements, and barium chloride having a higher purity than the conventional analysis value of the impurity concentration of barium chloride could be produced.

Example 4 Using barium chloride as a starting material, barium hydroxide (Ba (OH) ₂ .8H ₂ O) is prepared, and then barium chloride is prepared. Barium chloride 100g pure water 20
After dissolving in 0 ml and adding ammonium acetate, the pH was adjusted to 4.0 to 5.0, and 1 ml of a solution prepared by dissolving 1.0 g of DDDC in 10 ml of carbon tetrachloride and 50 ml of carbon tetrachloride.
ml removes transition metal impurities by solvent extraction. An ultrahigh-purity sodium hydroxide aqueous solution is added to the aqueous phase remaining after the extraction, and the mixture is cooled to form a barium precipitate. The barium precipitate can be recrystallized by filtration, heating and cooling.
Repeat 3 times to remove barium hydroxide (Ba (OH) ₂ · 8H ₂
O) Make crystals. Barium hydroxide (Ba (OH) ₂
8H ₂ O) is placed in 6N dilute hydrochloric acid, heated on a water bath, concentrated and then cooled to obtain crystals of barium chloride dihydrate. Barium chloride dihydrate, room temperature to 130 ℃
In the meantime, it is dehydrated and dried in a vacuum dryer to produce barium chloride. The chloride dihydrate can also be obtained by performing the above-mentioned extraction procedure using barium acetate, barium nitrate, or barium hydroxide as the starting material. In addition, the activation analysis of chromium, iron, cobalt, nickel, and copper in the prepared barium chloride was performed, and the analysis result of 1 ppb was obtained for 5 elements. It was possible to produce barium chloride of higher purity than that.

(Example 5) A method for producing high-purity barium fluorochloride using barium chloride as a starting material will be described with reference to the process chart of FIG. After dissolving 100 g of barium chloride in 200 ml of pure water and adjusting the pH to 4.0 to 6.0, solvent extraction of transition metal impurities with 10 ml of a solution of 1.0 g of DDTC in 100 ml of pure water and 50 ml of carbon tetrachloride. Eliminate with. The aqueous phase remaining from the extraction is added to hydrofluoric acid to produce a barium precipitate. The barium precipitate is decanted, filtered with a Teflon filter and dehydrated, and dehydrated and dried in a vacuum dryer at a temperature range of 30 ° C. to 150 ° C. to produce barium fluorochloride (BaFCl). In addition, activation analysis of chromium, iron, cobalt, nickel, and copper in the prepared barium fluorochloride was performed,
An analysis result of 1 ppb was obtained for the five elements, and barium chloride having a higher purity than the conventional analysis value of the impurity concentration of barium fluorochloride could be produced.

[0017]

As described above, according to the production method of the present invention, the water-soluble salt containing barium is used, and for each element of chromium, iron, cobalt, nickel and copper present in the aqueous solution, Since high-purity barium halide is produced by extracting and eliminating with the organic reagent and solvent that form the most stable complex, high-purity barium chloride and barium fluorochloride with extremely low transition metal concentrations are used. It was possible to manufacture. Further, by using this as a starting metal raw material of a fluoride optical fiber amplifier, there is an advantage that an optical fiber having a high amplification degree can be manufactured.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for producing high-purity barium chloride in Example 2.

FIG. 2 is a process drawing showing a method for producing high-purity barium chloride in Example 3.

FIG. 3 is a process drawing showing the method for producing high-purity barium chloride in Example 4.

FIG. 4 is a process drawing showing the method for producing high-purity barium fluorochloride in Example 5.

Claims (3)

[Claims] 1. In a method for producing high-purity barium halide, the pH of an aqueous barium solution is adjusted, and then dithiocarbamate having the following general formula: RCS ₂ R ₁ is added to extract and remove impurity transition metals to obtain impurities. A method for producing high-purity barium halide, which comprises producing barium halide from the aqueous barium solution from which transition metal has been extracted and removed. General formula: RCS ₂ R ₁ (wherein, R represents _{(C 2 H 5) 2 N-} ,
Or: R ₁ is H ₂ , NH ₄ ⁺ , NH ₂ ⁺ (C ₂ H ₅ ) ₂ ,
Indicates Na ⁺ . ) 2. The method for producing high-purity barium halide according to claim 1, wherein the high-purity barium halide is barium chloride or barium fluorochloride. 3. The method for producing high-purity barium halide according to claim 1, wherein the aqueous solution containing barium is composed of salts such as acetate, nitrate, chloride and / or hydroxide.