JPH01219008A - Production of selenium having high purity - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing high-purity selenium, which is supplied as a raw material for semiconductors and optical fibers.

[Conventional technology]

Conventionally, methods for producing high-purity selenium include vacuum distillation of ordinary grade metallic selenium, zone refining, or a combination of these methods. In particular, in the vacuum distillation method of ordinary grade metallic selenium, it is difficult to separate impurities such as sulfur, tellurium, and sodium, whose boiling points are relatively close to selenium, and it is difficult to achieve a purity of 99.9999% by weight or higher. This method also requires expensive equipment, leading to high costs.

[Problem to be solved by the invention]

An object of the present invention is to provide a manufacturing method for obtaining high purity selenium more easily than conventional methods.

[Means to solve the problem]

The present invention solves the above problems, and the monochloride obtained by passing chlorine gas through ordinary grade selenium or by treating a mixture of the selenium, selenium dioxide and hydrochloric acid with sulfuric acid to separate it as an oily liquid. When selenium is purified by distillation using a distillation machine, the initial distillation of selenium monochloride, which accounts for 5 to 15% by weight of the treated amount, is separated and removed, and then the distillation process is carried out again and the resulting fraction is used as the main distillation to purify selenium monochloride. The method is characterized in that selenium is recovered, purified selenium monochloride is subjected to a disproportionation reaction in pure water to obtain selenium, and the selenium is distilled in a hydrogen stream or in a vacuum.

[Effect]

Selenium is generally converted into selenium monochloride by reaction with chlorine gas, but it can also be made by reacting sulfuric acid with a mixture of selenium, selenium dioxide, and hydrochloric acid.

In the former chlorine gas method, when passing chlorine gas through selenium, it is desirable to heat the selenium to form a melt and blow chlorine gas into the melt. At this time, if a large excess of the chlorine gas is blown in at once, part of the selenium monochloride will change to selenium tetrachloride, so it is necessary to gradually bleed in the chlorine gas.For this purpose, it is desirable to react all of the selenium. It is best to leave some amount in the reaction vessel without putting it away. In addition, in the latter method, when sulfuric acid is applied to a mixture of selenium, selenium dioxide, and hydrochloric acid, its dehydration effect results in the following (
The reaction of formula I) proceeds to the right side and selenium monochloride 3Se + 5eO
z+4HCZ→2SezCj2g+2HzO(1) is produced, but this is an oily liquid and separates from the aqueous solution phase to form two phases, so if this oily selenium monochloride is separated using a separating funnel etc., it can be easily converted to monochloride. You can get selenium.

The selenium chloride is purified by distillation. When the processing amount is 5 to 15
The reason why we decided to separate and remove the initial distillate corresponding to 5% by weight is that if the ratio of the initial distillate to be removed is less than 5% by weight, low-boiling point impurities such as sulfur and phosphorus will remain in the main distillate. This is because it lowers the purity of high-purity selenium, which is contrary to the purpose.If the ratio of initial distillate removed exceeds 15% by weight, not only will the yield of available products decrease, but the improvement in product purity will also become less noticeable. This is because it becomes lacking. When the purified selenium monochloride is subjected to a disproportionation reaction in pure water, selenium becomes selenite and 25ezC1z as shown in the following formula (II).
+3+1zO-3Se+HzSe03+4 H(1(
II) Since selenium is produced together with hydrochloric acid, it is desirable to wash the selenite several times with cold or hot water to sufficiently remove the selenious acid and hydrochloric acid. Although the reaction (n) above proceeds at room temperature, it is preferable to carry out the reaction in hot water of 80° C. or higher because the reaction speed increases. The reason why the selenium obtained in the reaction (n) above is distilled is because a trace amount of selenium chloride remains in the selenium, and this is removed by distilling while flowing hydrogen or in a vacuum. It is important to ensure that this is done completely.

[Example-1] 1000 g of selenium with a purity of 99.99% by weight was placed in a 11 Pyrex flask and melted by heating, and chlorine gas was blown into the selenium melt through a capillary at a flow rate of 11/min. As the reaction progresses, the amount of the dark-colored selenium monochloride melt increases and pale yellow selenium tetrachloride begins to adhere to the top of the Pyrex flask. At this point, stop blowing in chlorine gas, blow in argon gas, and stir the liquid. A uniform melt was obtained. It was cooled to room temperature, unreacted selenium remained in the flask, and the obtained selenium monochloride was transferred to No. 11 Pyrex distillation pot, and distillation purification was performed while maintaining the distillation temperature at 142°C. After separating and removing 90g of selenium monochloride as the first distillate,
630 g of purified selenium monochloride was obtained. The obtained purified selenium monochloride was added to ultrapure water prepared in advance in a 5β pyrex beaker and heated to 90° C. or higher. At the beginning of the reaction, red selenium powder is produced, but it gradually turns black.
At the end of the reaction, 300 g of black massive selenium was obtained.

After washing this massive selenium with ultrapure water, a quartz board was placed inside a quartz furnace tube with an inner diameter of 110 mm, and selenium was placed inside the tube and heated to 500°C while flowing hydrogen gas at a rate of 217 minutes. We were able to obtain selenium condensed in a quartz boat placed in the low-temperature part of a quartz furnace tube. The mass spectrometry values of this purified selenium are shown in Table 1. ' [Example-2] 500 g of selenium with a purity of 99.99% by weight and 233 g of selenium dioxide were placed in a 51 Pyrex beaker, and 1 portion of hydrochloric acid was added.
After adding 300 cc, 1000 cc of sulfuric acid was added dropwise little by little while stirring strongly with a glass stirring rod. The oily selenium monochloride produced at the bottom of the beaker separated from the aqueous phase to form two phases, which were separated using a separating funnel to obtain 836 g of selenium monochloride. This selenium chloride is used in the following example.
Distillation purification, disproportionation reaction, and water washing were performed in the same manner as in 1 to obtain selenium, which was then distilled to obtain purified selenium.

The mass spectrometry values of this purified selenium are shown in Table 1.

As a comparative example, mass spectrometry values of selenium obtained by conventional vacuum distillation are also shown in Table 1.

〔Effect of the invention〕

As is clear from the mass spectrometry results, the method of the present invention has a remarkable purification effect on many impurity elements in general, and it is extremely easy to obtain high-purity selenium with a purity of 99.9999% by weight or more. It becomes possible.

Patent applicant: Sumitomo Metal Mining Co., Ltd.

Claims (1)

[Claims] (1) By passing chlorine gas through ordinary grade selenium or by treating a mixture of selenium, selenium dioxide, and hydrochloric acid with sulfuric acid and separating it as an oily liquid, the obtained selenium monochloride is purified by distillation using a distillation machine. In this process, after separating and removing the initial fraction of selenium monochloride, which accounts for 5 to 15% by weight of the treated amount, the distillation process is carried out again, and the obtained fraction is used as the main fraction to recover purified selenium monochloride. A method for producing high-purity selenium, which comprises performing a disproportionation reaction on selenium monochloride in pure water to obtain selenium, and distilling the selenium in a hydrogen stream or in vacuum.