JP2001259373A - Method for gasifying treatment of solid product in laser isotope separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the gasifying treatment of a solid product, rapidly removing the solid product when the solid product formed in laser isotope separation adheres to a laser isotope separator to enable the smooth continuation of laser isotope separation work and capable of facilitating the recovery of the solid product. SOLUTION: A solid substance formed by the decomposition of a work substance in laser isotope separation is exposed to a halogenating agent injected form a halogenating agent injection device 13 to be gasified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for chemically converting a solid substance produced in laser isotope separation into a halogen compound (fluorine compound) using a halogenating agent (fluorinating agent), and vaporizing and recovering the same. .

[0002]

2. Description of the Related Art A powerful method of laser isotope separation includes a method called an atomic method and a method called a molecular method. Focusing on the difference in light absorption between isotope atoms different from the atomic method, it selectively excites specific isotope atoms, and finally separates and enriches them. Focusing on the difference in optical absorption between molecules containing isomers, selectively excite molecules containing specific isotopes, leading to reactions, and separating and enriching the isotopes in products or unreacted products Is the way.

[0003] In the molecular method, a photochemical phenomenon called infrared multiphoton decomposition in polyatomic molecules was found, and since a large isotope effect was confirmed in that phenomenon, a great deal of attention has been paid, and enormous research worldwide has been carried out on a laboratory scale. Has been tried in However, research on separation / concentration using practical models is still extremely scarce.

[0004] Laser isotope separation on a practical scale by the molecular method includes the silicon isotope ²⁸ Si based on the isotope-selective infrared multiphoton decomposition of hexasilane disilane Si ₂ F ₆ induced by a carbon dioxide gas laser. , ²⁹ Si and ³⁰ Si etc. (M. kamioka, Y. Ishikawa, H. Kaetsu,
S. Isomura, and S. Arai, J. Phys. Chem., 90, 5727 (198
6); Patent Publication H2-56133) is well known.

[0005] Natural silicon is 92.2% ²⁸ Si,
Consisting of 4.7% ²⁹ Si, 3.1% ³⁰ Si. In the silicon of the silicon compound around us, ²⁸ Si, ²⁹ Si and ³⁰ Si are present at this ratio.

[0006] Si ₂ F ₆ which is a compound of silicon and fluorine
Has an infrared absorption band in the oscillation region of the carbon dioxide gas laser due to the stretching vibration of the SiF bond, and the position of the band has a so-called isotope shift between ²⁸ SiF, ²⁹ SiF and ³⁰ SiF with respect to wavelength.

950 cm in Si ₂ F ₆ at a low pressure of about several torr
^When irradiated with a pulsed light beam of a CO2 laser near ^{-1 or a} high fluence pulse beam, each molecule absorbs a dozen or more photons during the pulse period, resulting in a highly excited state. And the SiF expressed by the equation (1)
Decomposes into ₂ and SiF ₄ . This is infrared multiphoton decomposition of Si ₂ F ₆ . SiF ₂ is an unstable molecule and polymerizes one after another to form a white solid powder having a composition of (SiF ₂ ) _m . Here, m represents the number of polymerizations.

[0008]

Embedded image Si ₂ F ₆ + nhν → SiF ₂ + SiF ₄ (1)

M SiF ₂ → (SiF ₂ ) _m (2) In the infrared multiphoton decomposition, ²⁹ Si and ³⁰ Si are highly concentrated in the product SiF _{4 as} a result of the isotope effect in multiphoton absorption. On the other hand, ²⁸ Si is highly concentrated in unreacted Si ₂ F ₆ .

The fluence of the pulsed light indicates the energy of the pulse per unit area in the cross section of the laser beam, and its value is extremely large near the focal point of the focused laser beam.

In other words, infrared multiphoton decomposition is only possible at fluences in which a large number of laser photons hit individual molecules during a laser pulse.

Utilizing this isotope-selective infrared multiphoton decomposition of Si ₂ F ₆ , continuous supply of raw materials, recovery of products,
Attempts have been made to separate and concentrate silicon isotopes on a practical scale by combining laser irradiation and the like.

[0012]

In laser isotope separation, which is generally called a molecular method, gas molecules are irradiated with high fluence laser light to create a condition in which a large number of photons collide with individual molecules of a working material. Although it is necessary, in the course of the reaction following the excitation of the gas molecules, the reaction of equation (2) produces a solid product, which results in clouding of the entrance window of the laser beam, reduction of the collision of photons, and In some cases, clogging or the like of a gas flow path may occur, making it impossible to continue separation. For example, in the above-mentioned separation of silicon isotopes, a solid product represented by (SiF ₂ ) _m is formed. Usually, the clogging by the solid product is performed by exposing the separation device to the atmosphere to open the inside and remove it. However, there is a problem that much work and time are required until the device is assembled and separation is started again. Further, since this solid product (SiF ₂ ) _m contains a high concentration of isotope,
Although it is preferable to recover the isotope in increasing the yield of the isotope, a suitable technique for performing the recovery has not been developed. In such circumstances, hexafluorinated disilane S
The same applies to laser isotope separation of working substances other than i ₂ F ₆ .

The present invention has been made in view of the above-mentioned circumstances, and when a solid product generated in laser isotope separation adheres to a laser isotope separation device, the solid product is promptly removed and removed. It is an object of the present invention to provide a method for treating a solid product, which enables the isotope separation operation to be continued smoothly and facilitates the recovery of the solid product.

[0014]

SUMMARY OF THE INVENTION In accordance with this object, a method for gasifying a solid product in laser isotope separation according to the present invention comprises the steps of: It is characterized by being gasified by exposure to a halogenating agent.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings showing embodiments. In FIG. 1, reference numeral 1 denotes a laser isotope separation device. This apparatus is roughly classified into a laser section 5, which comprises a laser generator 2, an infrared lens 3, and a laser intensity detector 4, an inert gas injection nozzle 6, a reaction vessel 7, a supply pipe 8 for a working substance, that is, a raw material gas, and a derivation of a reaction gas. A reaction section 10 composed of a pipe 9, a halogenating agent filling device 11, a halogenating agent injection device 13 including a valve 12, a raw material gas injection port 14,
An exhaust device 15, a pressure gauge 16, a working substance or raw material gas storage container 17, a pressure control device 18, a flow control device 19,
A working substance supply unit 21 including a flow meter 20, a pressure control device 22, a low temperature collector 23, a reactive gas recovery unit 26 including an exhaust device 24, a low temperature distillation device 27, an unreacted working material storage container 28, a generated gas storage container The reaction gas separation section 30 is composed of 29. The laser beam from the laser generator 2 can irradiate the working substance in the reaction vessel 7, that is, the raw material gas, through the infrared lens 3. The inert gas injection nozzle 6 is provided for the purpose of preventing solid products from adhering to the window on which the laser beam enters, and injects, for example, nitrogen gas or argon gas during laser irradiation. A halogenating agent injecting device 13 is attached to the supply pipe 8 for the working substance, that is, the raw material gas.

The operation of laser isotope separation and the removal and recovery of solid products in the laser isotope separation apparatus 1 constructed as described above are performed as follows. The working substance is supplied from the supply pipe 8 for the working substance, that is, the raw material gas to the reaction vessel 7.
When the work material is irradiated with the laser beam from the laser generator 2 while supplying the work material, the isotopes in the work material are separated and concentrated in the product or the unreacted work material. The mixture of the product and the unreacted work material is collected in the low temperature collector 23 through the reaction gas outlet pipe 9. This mixture is then sent to a cryogenic distillation unit 27, where it is separated into product and unreacted working material.

Products containing specific isotopes separated and produced in the reaction vessel 7 by laser irradiation may be solids, and these solid products are used as the reaction vessels 7 and 7.
The reaction gas outlet pipe 9 on the downstream side, the pressure control device 22,
As described above, it may adhere to the low-temperature collector 23 or the like and hinder the continuation of isotope separation. Therefore, in order to solve this problem, in the present invention, when the solid product interferes with the continuation of the isotope separation, the laser generator 2 is used.
Is stopped, and the introduction of the raw material gas into the reaction vessel 7 is stopped, and the product condensed in the low-temperature collector 23 and the unreacted raw material gas are transferred to the low-temperature distillation device 27 and cleaned. Next, after cooling the low-temperature collector 23, the valve 12 at the outlet of the halogenating agent filling device 11 is opened, and the adhered solid product is exposed to a halogenating gas such as fluorine, for example. The substance is chemically converted into low molecular weight gas molecules and removed.

The halogenating agent itself is a gas, and any product can be used as long as the product in the halogenation of a solid product is a gas.
_{F 2, ClF, ClF 3,} Cl 2, BrF, like BrF _5.

The relevant part of the separation device that is exposed to the halogenating agent must be inert to the halogenating agent or significantly inert compared to the solid product. Some solid products formed following selective excitation by the laser include:
Often specific isotopes are enriched. For example, Si ₂
In the infrared multiphoton decomposition of F ₆ under the appropriate conditions,
(SiF ₂₎ ²⁹ to the solid product of the composition of _m Si and ³⁰ S
i is highly concentrated. Therefore, it is necessary to recover the gas generated by the halogenation of (SiF ₂ ) _m , and a general method such as condensation and collection by a low-temperature trap or adsorption and collection by an adsorbent can be used for the recovery. Here, it is collected in a pre-cooled collector.

[0020]

[Experimental Examples] (1) Based on the isotope-selective infrared multiphoton decomposition of Si ₂ F ₆ using a carbon dioxide gas laser, a large amount of ³⁰ Si was concentrated in the product SiF ₄ using a flow method. The pulse light of the carbon dioxide laser is 10P with a wave number of 951.19 cm ^-1 .
(12) line, the output of which was 23.5 W at 5 Hz pulse repetition. The laser beam was condensed by an infrared lens having a focal length of about 2 m, and was irradiated onto Si ₂ F ₆ at a pressure of several torr. During laser irradiation, a large amount of nitrogen gas was constantly blown onto the laser entrance window to prevent clouding.

The SiF ₄ is collected together with the unreacted Si ₂ F ₆ in a trap cooled with liquid nitrogen and collected.
The SiF ₄ was separated and recovered by fractionation at 5 ° C.
Mass spectrometry revealed that ³⁰ Si was concentrated to 9.4% in F ₄ . A large amount of white solid product adhered from the reaction vessel to the trap, and accumulated in a large amount especially in the valve, obstructing the flow. When exposed to the halogenating agent F ₂ , SiF ₄ is generated, and further generated SiF ₄
As a result of measuring ₄ with a mass spectrometer, it was found that ³⁰ Si was concentrated to about 9.0%, and that ³⁰ Si was also concentrated in the original solid product.

(2) Based on isotope-selective infrared multiphoton decomposition of Si ₂ F ₆ by a carbon dioxide laser, a large amount of ³⁰ Si was concentrated in the product SiF ₄ by employing a flow method. The pulsed light of the carbon dioxide gas laser has a wave number of 951.19 cm ^-1 .
P (12) line, the output of which was 23.5 W at 5 Hz pulse repetition. The laser beam was condensed by an infrared lens having a focal length of about 2 m, and was irradiated onto Si ₂ F ₆ at a pressure of several torr. During laser irradiation, a large amount of nitrogen gas was constantly blown onto the laser entrance window to prevent clouding.

SiF_FourIs unreacted Si_TwoF₆With liquid nitrogen
Aggregated and collected in a trap cooled with hydrogen, then -9
Fractional distillation at 5 ° C_FourWas separated and recovered.
F_Fourinside,³⁰Si is concentrated to 12% by mass
It became clear from the result of the analysis. Trap from reaction vessel
Large amount of white solid product adheres up to
Had accumulated in large quantities and had been impeding distribution. Entire distribution channel
To Cl_TwoExposure to SiCl_TwoF_TwoOccurs and further occurs
SiCl_TwoF_TwoAs a result of measuring with a mass spectrometer, ³⁰Si
Is concentrated to about 10%, and is contained in the original solid product.
Also³⁰It became clear that Si was concentrated. C
l_TwoIs F_TwoUnlike glass, it is inert to glass.
It is possible to remove solids adhering to the part of the device.

[0024]

In according to the present invention for example Si ₂ ²⁸ with isotopes selective infrared multiple photon decomposition of ^{_{F 6 Si, 29 Si, 30}} Si separation and concentration, such as, solid product of the pressure and flow meter, the control valve ,
Blocking the distribution channel is a major problem. In that case, the separation device is dismantled and removed in the conventional technology, but during the work of exposing the inside to the atmosphere, toxic gas is generated, and unexpected problems such as adsorption of atmospheric moisture into the inside occur. This causes delays in the work of the main separation. As a result of the present invention, it is possible to remove solid products without dismantling the separation device in the future, which saves labor and increases work safety. Si ₂
Experimental examples have revealed that silicon isotopes are enriched in solid products produced by infrared multiphoton decomposition of F ₆ , as in the gaseous product SiF ₄ .

Therefore, if the solid product is vaporized with a halogenating agent and the gas is recovered, the yield of the isotope is doubled. The recovery operation is also simple, and the gaseous substance generated by halogenation of the solid product with the halogenating agent may be collected by a low-temperature trap or the like, and then the halogenating agent and the generated gaseous substance may be separated.

The vaporization of the solid product by the halogenating agent is
More than just removing fogging of windows and clogging in distribution channels,
This leads to an increase in the isotope yield, and the effect of the invention is extremely large. The same applies to the case of laser isotope separation of a working material other than Si ₂ F ₆ .

[0027]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of a laser isotope separation apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser isotope separation apparatus 2 Laser generation apparatus 3 Infrared lens 4 Laser intensity detector 5 Laser part 6 Inert gas injection nozzle 7 Reaction vessel 8 Supply pipe of working material, that is, raw material gas 9 Reaction gas outlet pipe 10 Reaction section 11 Halogen Agent filling device 12 Valve 13 Halogenating agent injector 14 Source gas inlet 15 Exhaust device 16 Pressure gauge 17 Working substance, ie, source gas storage container 18 Pressure controller 19 Flow controller 20 Flow meter 21 Working substance supplier 22 Pressure control Apparatus 23 Low temperature collector 24 Exhaust device 26 Reactive gas recovery unit 27 Low temperature distillation device 28 Unreacted work material storage container 29 Product gas storage container 30 Reactive gas separation unit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Akio Oya 662-12, Funashikikawa, Tokai-mura, Naka-gun, Ibaraki Pref. Inside Nukuria Development Co., Ltd. (72) Inventor Shigeyoshi Arai 4-6-1 Roppongi, Minato-ku, Tokyo F-term in Hill Research Co., Ltd. (reference) 4G072 AA08 GG03 HH05 JJ04 MM01 RR01 RR11 UU30

Claims (6)

[Claims] 1. A method for gasifying a solid product in a laser isotope separation operation, comprising exposing a solid substance produced by decomposing a work material in the laser isotope separation to a halogenating agent and gasifying the solid substance. 2. The gasification treatment method for a solid product according to claim 1, wherein the gasified solid substance is recovered. 3. In laser isotope separation using a laser isotope separation device, a solid substance produced by decomposition of a working material and attached to the laser isotope separation device is exposed to a halogenating agent to be gasified. A method for gasifying a solid product, wherein the gas is removed from the laser isotope separation apparatus. 4. The gasification treatment method for a solid product according to claim 3, wherein the gasified solid substance is recovered. 5. A silicon fluoride polymer ｛(SiF ₂ ) _m formed by laser isotope separation of hexafluorodisilane
: M is a method for gasification of a solid silicon fluoride material, comprising exposing a few｝ of the polymerization to a halogenating agent to convert them into gas molecules of low molecular weight. 6. The method according to claim 5, wherein the gas molecules are recovered.