RU2227061C1 - Method of thallium isotopes separation in an electromagnetic separator - Google Patents

Abstract

FIELD: industrial separation of thallium isotopes. SUBSTANCE: the invention presents a method of separation of thallium isotopes, that may be used for industrial separation of thallium isotopes. In the crucible of a source of ions a working substance - a charge of thallium chloride of 300 g mass is placed. Then it is heated up to a vaporous state. The vapors are being ionized in the gas-discharge chamber of the source under action of an electron emission from a thermocathode. Electrodes of an ionic-optical system form an ion beam, then the ionic beams of isotopes are separated and focused in a magnetic field and the receiver boxes trap them. Magnitude of the ionic current coming to the receiver boxes is maintained within the limits of 35-50 mA, accumulation by the receiver boxes is increased up to 6500-7500 mA/h. A ratio of an ionic current of the isotopes coming to the receiver boxes to the ionic current accumulated on the basic adjusting electrode and on the additional electrode is maintained within the limits of 170-200 mA/h. The invention allows to increase productivity by 30 % without decrease of enrichment of the separated isotopes, to increase durability and service life of boxes of the receiver. EFFECT: increased productivity by 30 % without decrease of enrichment of the separated isotopes, increase durability and service life of the receiver boxes. 3 cl, 2 dwg, 1 tbl

Description

The invention relates to the technology of electromagnetic separation of isotopes of chemical elements, and more specifically to electromagnetic separation of thallium isotopes.

The invention can most effectively be used for industrial separation of stable isotopes: thallium-203, thallium-205.

A known method for the separation of isotopes of various chemical elements, used for industrial electromagnetic separation of isotopes and providing for the heating of the crucible with the working substance and the gas discharge chamber by thermal radiation from heaters of the active resistance to the formation of steam of the working substance, ionization of molecules in the gas discharge chamber from which ions are extracted and formed into ion a beam separated and focused by a magnetic field in accordance with the mass of isotopes and captured by the receiver boxes (N.A. Kashcheev, .A.Dergachev electromagnetic separation of isotopes and isotope analysis -.. M .: Energoatomisdat, 1989).

One of the disadvantages of this method is that it is not effective enough due to its low productivity, in particular for the separation of thallium isotopes.

As a working substance, thallium chloride (TlCl) is loaded into the crucible. When heated, vapors of its substances get from the crucible through the steam distribution plate into the gas discharge chamber of the source, where they are ionized and the subsequent separation of isotopes, as described above.

The main parameters that determine the effectiveness of the electromagnetic separation method are its performance and enrichment of the resulting isotopes. The first parameter is determined by the isotope ion current arriving at the receiver boxes (Iq), the installation time utilization factor (Qivr), and isotope capture coefficients (Ku).

The second parameter is determined by the ratio of the ion current of the isotopes coming to the receiver boxes (Iq) to the ion current to the main tuning electrode (Ione) and is expressed by the formula (Sone = Ibq / Ione). In particular, the higher the Sone, the better the focus or the higher the degree of focus on the main tuning electrode.

These two parameters are not independent and significantly affect each other. The indicated dependence is ambiguous and for each chemical element at different ranges of ion current of isotopes can decrease or increase.

At the same time, the dependence connecting this ratio and the enrichment of the resulting isotopes is nonlinear due to the influence of additional factors: charge exchange of ions during passage through the separation chamber of the separator, their neutralization in the ion beam, ion scattering on residual gas molecules, etc.

For example, the combined dependence - enrichment of the isotope T1-203 (C,%) on the magnitude of the ion current of isotopes on the receiver boxes shows (see Fig. 1 and table) that to obtain isotopes of high enrichment it is not always necessary to work with low currents and a high ratio Sone.

In this case, the productivity of the method comes to the fore, determined mainly by the magnitude of the ion current of isotopes on the receiver boxes. However, an increase in the ion current of isotopes reduces the operating time of the receiver due to faster accumulation of isotopes in its boxes and “burning” of their walls due to ion sputtering. Because of this, it is necessary to change the receivers more often, even in the case when the sources have not yet exhausted their resource, which leads to a decrease in the utilization factor of the installation’s operating time, and therefore to its productivity.

This problem is caused, in particular, by the fact that when separating thallium isotopes (see figure 2 is a view from the entrance to the receiver boxes), the main tuning electrode (item 1) is made in the form of a molybdenum rod with a diameter of 3 mm, an effective length of 90 mm and is installed in the lower part between the ends of the conjugate walls of the T1-203 and T1-205 boxes (pos. 2, 3) of the receiver, which have an entrance with a height of 180 mm, and also between the other electrodes - “light frame” (pos. 4) and “ heavy benchmark ”(pos. 5) installed along the edges of these boxes in order to prevent the displacement of beams from opov.

This design of the receiver, in turn, does not guarantee a uniform distribution of the density of ion beams of isotopes along the height of the boxes, which causes increased wear of the walls of the boxes of the receiver in places of increased density. At the same time, this makes it necessary to limit the ion current of the isotope beams to the receiver boxes, on the one hand, since the degree of focusing and the density of these beams in the uncontrolled part of the receiver boxes are unknown - in case the beam density is higher there and the degree of focusing is less. On the other hand, at the maximum ion current to the main tuning electrode, the magnitude of the ion current of isotopes to the receiver boxes is limited by the specified Sone ratio.

The installation of a one-piece main tuning electrode across the entire height between the receiver boxes does not eliminate the indicated unevenness and additionally leads to its deformation, which contributes to the isotopic contamination of neighboring boxes.

The objective of the invention is to increase the performance of the electromagnetic method for the separation of thallium isotopes and increase the resistance of the boxes of the ion receiver.

The technical result is achieved due to the fact that the ion current of isotopes to the receiver boxes is maintained within 35-50 mA, and the ratio of the ion current of isotopes coming to the receiver boxes to the ion current to the main tuning electrode is maintained within 170-200. In the upper part between the boxes of the receiver, an additional DF 1 electrode is installed (Fig. 2, item 6) of the same diameter and slightly shorter than the main tuning electrode, which ensures a guaranteed thermal gap between them (see table), and the ratio of the ion current of isotopes on the receiver boxes to the ion current to the additional electrode (Сдф1 = Iбк / Iдф1) support within the same limits as on the main tuning electrode by adjusting the operation parameters of the ion source.

As a result of this redistribution, isotope enrichment practically does not decrease, and the resistance of the walls of the boxes of the receiving unit increases, and the accumulation of isotopes on them increases accordingly.

The analysis of publicly available sources of information about the prior art did not allow to identify a technical solution identical to the claimed one, on the basis of which it is concluded that the latter is unknown, i.e. compliance presented in this application of the invention with the criterion of "novelty."

A comparative analysis of the claimed solution with known technical solutions revealed that the presented set of distinctive features is unknown to a person skilled in the art and does not follow explicitly from the prior art, on the basis of which it is concluded that the invention presented in this application meets the criterion of “inventive step”.

To illustrate the invention, an embodiment of the method is provided below. It was tested during the separation of thallium isotopes in the electromagnetic separator SU-20 of the Elektrokhimpribor plant, Lesnoy, Sverdlovsk Region.

A 300 g sample of thallium chloride was placed in the crucible of the ion source. After installing the source and the receiver with two boxes with the main and additional electrodes (see figure 2) in the separation chamber of the separator, the chamber was pumped out with vacuum pumps to a pressure of (1-2) · 10 ^-3 Pa and a high-voltage training of the source to a voltage of 31-33 kV

After receiving the electron beam in the gas discharge chamber of the source, voltages were applied to the crucible and gas discharge heaters, which ensured the evaporation of the working substance, its ionization in the gas discharge chamber, and the formation of an ion beam using two ion-optical systems consisting of two ion beams of isotopes, which under the action of accelerating voltage 31-33 kV and a constant magnetic field in a chamber of the order of 3533 Oe were separated, focused in the focal plane and captured by receiver boxes. The accumulation on the receiver boxes was 6500-7500 mAh against 5000-6000 mAh according to the prototype.

After accumulation, the receivers were removed from the separation chamber, isotopes were removed from the boxes, the isotope-enriched solution was analyzed for enrichment and for the content of thallium in it.

The results of the experimental industrial separation of thallium isotopes are shown in the table on the example of a stable thallium-203 isotope.

Thus, the proposed method of electromagnetic separation of thallium isotopes in comparison with the existing method has shown its effectiveness in obtaining a technical and economic result. Use

the practical application of the proposed technical solution can significantly (by 30%) increase its productivity practically without reducing the enrichment of the shared isotopes, as well as increase the resistance of the ion receiver boxes. The implementation of the claimed technical solution is possible on existing equipment without additional staff training for work skills.

Claims (3)

1. The method of separation of thallium isotopes in an electromagnetic separator, including placing the working substance in the crucible of the ion source, heating the working substance to a vapor state, ionizing the vapor of the working substance in the gas discharge chamber of the source under the influence of electron emission from the thermal cathode, forming the ion beam by electrodes of the ion-optical system, separation and focusing of ion beams of isotopes in a magnetic field, trapping of these beams by receiver boxes, characterized in that the ion current of isotopes to the receiver boxes Single maintained between 35-50 mA, and the ratio of isotopes of the ion current arriving at the receiver box to the ion current in the main adjusting electrode is maintained in the range 170-200. 2. The method according to claim 1, characterized in that the ratio of the ion current of the isotopes coming to the receiver boxes to the ion current on the additional electrode is set within the same limits as on the main tuning electrode. 3. The method according to claims 1 and 2, characterized in that the accumulation on the receiver boxes is increased to 6500-7500 mA · h.

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