RU2254390C1 - Method of production of metallic magnesium - Google Patents

Abstract

FIELD: production of stable isotopes; production of isotope-enriched magnesium.

SUBSTANCE: metallic magnesium is produced by drying and calcination of magnesium oxide, preparation of charge containing MgO-Al-rare-earth metals, pressing the charge for forming tablets, reduction of oxide and vacuum distillation of magnesium; rare-earth metal is taken in the amount of 10-15 mass-%. Calcination of magnesium is performed at temperature of 750-850°C and pressure of 5-10 mm Hg continued for 2-3 h. Reduction process is conducted at residual pressure of 10^-5-10^-6 mm Hg and temperature of 1050-1150°C continued for 15-20 h and excess of reductant relative to stoichiometry in the amount of 15-20%.

EFFECT: increased degree of reduction of magnesium oxide; reduced losses of expensive isotope.

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Description

The invention relates to a technology for the production of stable isotopes, in particular to a technology for producing isotopically enriched magnesium, and can be used to obtain stable magnesium isotopes in metallic form.

Known methods (Belyaev A.I. et al. Metallurgy of pure metals and elementary semiconductors. - M .: Metallurgy, 1969, p.41-44), with which you can get magnesium in the form of a metal. These methods include the reduction of magnesium by electrolysis or metallothermic reduction by ferrosilicon. The disadvantages of these methods are:

- the need for additional refining of the obtained metal;

- the inability to quantitatively transfer small amounts of magnesium isotope oxide into the metal.

The use of ferrosilicon does not allow to achieve high metal yields.

At the same time, there is a method for producing magnesium in metallic form, which includes drying and calcining magnesium oxide, preparing a mixture containing magnesium oxide and a reducing agent, compressing the mixture into a tablet, reducing magnesium oxide, vacuum distillation of magnesium (RU 2017844 C1, C 22 B 26/22, 08/15/1994, 5 pp.) The specified method is taken as a prototype as the closest to the claimed method and is characterized by high efficiency.

Significant disadvantages of the prototype method are:

- low yield of magnesium in the form of a metal;

- the difficulty of extracting magnesium from the residues of the reaction mass due to the formation of strong oxide compounds of magnesium-aluminum, which leads to irretrievable losses of magnesium.

Thus, there is a technical problem, which is expressed in the fact that there is no high-performance method for producing magnesium in metallic form with minimal losses.

The objective of the proposed technical solution is to develop a method for producing isotopically enriched magnesium in metallic form.

The problem is solved in that magnesium in a metal form is obtained by drying and calcining magnesium oxide, preparing a mixture of MgO-Al-REM (rare-earth metal), pressing the mixture into a tablet, and reducing the oxide of vacuum distillation of magnesium. In this case, rare earth metal is taken in an amount of 10-15 weight percent. Magnesium oxide is calcined at a temperature of 750-850 ° C and a pressure of 5-10 mm Hg. within 2-3 hours. The recovery process is carried out at a residual pressure of 10 ^-5 -10 ^-6 mm RT.article. at a temperature of 1050-1150 ° C for 15-20 hours and an excess of reducing agent in relation to stoichiometry in the amount of 15-20%.

The analysis of publicly available sources of information on the level of technology did not allow us to identify a technical solution identical to the declared one, on the basis of which we conclude 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".

The following are examples of the implementation of the proposed method. Neodymium was used as a representative of the REM group.

Example 1. Table 1 shows the results of experiments on the reduction of magnesium oxide with a mixture of aluminum and neodymium. The recovery process was carried out at a temperature of 1100 ° C and a residual pressure of 2 · 10 ^-5 mm RT.article. within 18 hours with an excess of reducing agent in relation to stoichiometry -20%. The neodymium content in the reducing agent mixture was varied.

Table 1 The effect of the neodymium content in the reducing agent on the degree of reduction of magnesium oxide The concentration of neodymium in the alloy, wt.% 0 5 10 12.5 fifteen twenty The degree of recovery,% 91 95 97 97 98 98

Example 2. Table 2 shows the results of experiments on calcination of magnesium oxide at atmospheric pressure for 1 hour.

table 2 The effect of calcination temperature on the magnesium content of magnesium oxide powder Temperature ° C 650 700 750 800 850 900 The concentration of magnesium in powder,% 59.3 59.5 60.0 60.0 60.1 60.1

Example 3. Table 3 shows the results of experiments on calcination of magnesium oxide at atmospheric pressure and a temperature of 800 ° C.

Table 3 Effect of calcination time on magnesium content in oxide powder Calcination time, hour 1 2 2,5 3 4 The concentration of magnesium in powder,% 60.0 60.1 60,2 60.3 60.3

Example 4. Table 4 shows the results of experiments on calcination of magnesium oxide at a temperature of 800 ° C for 2 hours.

Table 4 Effect of residual pressure during calcination on the magnesium content of magnesium oxide powder Residual pressure, mmHg 760 100 10 5 1 The concentration of magnesium in powder,% 60.3 61,4 61.7 61.8 61.8

Example 5. Table 5 shows the results of experiments on the reduction of magnesium oxide with a mixture of aluminum and neodymium with the content of the latter in the amount of 10 wt.%. The reduction process was carried out at a temperature of 1100 ° C for 18 hours with an excess of reducing agent in relation to stoichiometry - 20%.

Table 5 The effect of residual pressure during reduction on the degree of reduction of magnesium oxide The residual pressure of the recovery process, mm Hg 5 · 10 ^-4 1 · 10 ^-4 5 · 10 ^-5 1 · 10 ^-5 5 · 10 ^-6 1 · 10 ^-6 The degree of recovery,% 93 95 96 97 97 97

Example 6. Table 6 shows the results of experiments on the reduction of magnesium oxide with a mixture of aluminum and neodymium with the content of the latter in the amount of 10 wt.%. The recovery process was carried out at a temperature of 1100 ° C and a residual pressure of 2 10 ^-5 mm RT.article. within 18 hours.

Table 6 The effect of excess reducing agent on the degree of reduction of magnesium oxide Excess reducing agent,% 0 5 10 fifteen twenty 25 The degree of recovery,% 75 84 91 96 97 97

Example 7. Table 7 shows the results of experiments on the reduction of magnesium oxide with a mixture of aluminum and neodymium with a content of the latter in the amount of 10 wt.%. The recovery process was carried out at a temperature of 1100 ° C and a residual pressure of 2 · 10 ^-5 mm RT.article. and an excess of reducing agent with respect to stoichiometry in an amount of 20%.

Table 7 Effect of recovery time on the degree of reduction of magnesium oxide Recovery time, hour 12 14 16 eighteen twenty 22 The degree of recovery,% 93 95 96 96 97 97

Example 8. Table 8 shows the results of experiments on the reduction of magnesium oxide with a mixture of aluminum and neodymium with the content of the latter in the amount of 10 wt.%. The recovery process was conducted at a residual pressure of 2 · 10 ^-5 mm Hg. within 18 hours and an excess of reducing agent in an amount of 20%.

Table 8 The influence of the temperature of the reduction process on the degree of reduction of magnesium oxide Temperature ° C The degree of recovery,% The concentration of aluminum in the final product, 10 ² wt.% 800 eleven 0.001 900 25 0.005 1050 95 0.019 1100 97 0.11 1150 98 0.21 1200 98 2.0

The decrease and increase in the content of rare earth metal in the mixture in excess of the specified values is impractical. In the first case, the efficiency of the process decreases (the degree of magnesium reduction decreases). With an increase in the content of rare-earth metals over the specified content, there is no increase in the positive effect. With a decrease in the calcination temperature of magnesium oxide, a decrease in the calcination time and an increase in the residual pressure, the concentration of magnesium in the powder decreases. An increase in the calcination temperature, calcination time, and a decrease in the residual pressure in excess of these norms are also impractical, since it does not lead to an increase in the positive effect (to an increase in the magnesium content in the powder). An increase in the residual pressure during the reduction of magnesium, a decrease in the exposure time, a decrease in the excess of the reducing agent with respect to stoichiometry, and a decrease in temperature lead to a decrease in the degree of reduction of magnesium. A decrease in the residual pressure during the reduction of magnesium oxide, an increase in the exposure time and an increase in the excess of the reducing agent with respect to stoichiometry in excess of the above does not lead to a further increase in the degree of reduction and is impractical. In addition, an increase in the reduction temperature above 1150 ° C leads to a sharp increase in the aluminum content in magnesium, which is undesirable.

Using the proposed method allows to achieve a technical result, which is expressed in:

1. Increasing the degree of reduction of magnesium oxide;

2. Reducing the irrevocable loss of an expensive isotope.

Data comparing the proposed method and the prototype method are given in table.9.

Table 9 Comparative data on the implementation of the proposed method and the prototype method Process parameter Way prototype claimed 1. The degree of recovery of magnesium oxide,% 84 93 2. The irretrievable loss of magnesium,% 4.9 2,3

The claimed method can be implemented on standard equipment in an industrial enterprise.

Claims (1)

A method of producing magnesium in metallic form, including drying and calcining magnesium oxide, preparing a mixture containing magnesium oxide and a reducing agent, compressing the mixture into a tablet, reducing magnesium oxide, vacuum distillation of magnesium, characterized in that a mixture of aluminum and rare-earth metal is used as a reducing agent, the content of which in the mixture is 10-15 wt.%, the recovery is carried out at a residual pressure of 10 ^-5 -10 ^-6 mm Hg, at a temperature of 1050-1150 ° C for 15-20 hours and with an excess of reducing agent in the ratio ju to stoichiometry in the amount of 15-20%, and the calcination of magnesium oxide is carried out at a temperature of 750-850 ° C and a pressure of 5-10 mm Hg within 2-3 hours