KR100198976B1 - Method of removing ruthenium compounds in industrial waste gas - Google Patents

Abstract

The present invention is an exhaust gas generated during an industrial catalytic process, a dry treatment of spent nuclear fuel, or a solidification process of ruthenium-containing high-level wastes by using a collector prepared by mixing lithium, sodium, potassium, and yttrium rubidium compounds alone or in combination. It is related with the method of removing the ruthenium compound.

In the present invention, lithium, sodium, potassium, yttrium rubidium and the like in the trapping material react with ruthenium oxide to convert ruthenium oxide into a very stable compound even at high temperature, thereby removing ruthenium oxide in the exhaust gas. By collecting ruthenium oxides, ruthenium oxide can be removed very efficiently. The use form of these collectors can be used by molding into a particulate, supported, foamed or honeycomb monolith type or the like depending on the flow conditions of the exhaust body.

Description

Removal method of ruthenium compound in industrial exhaust gas

Figure 1a shows the thermogravimetric analysis (TG) for Y ₂ Ru ₂ O ₇ .

Figure 1a shows the thermogravimetric analysis (TG) for Li ₂ RuO ₃ .

[Purpose of invention]

[Technical field to which the invention belongs and the prior art in that field]

The present invention relates to a method for removing ruthenium oxide which is a toxic substance present in industrial exhaust gas, characterized by using a trapping material prepared by mixing alone or a mixture of lithium, sodium, potassium, yttrium and rubidium compounds.

Ruthenium oxides are the industry-end process and instructions for use in the field with the oxidation catalyst there is discharged from the fuel a dry process or a solidification process of the ruthenium-containing high-level waste, ruthenium 4 oxides of these (RuO ₄₎ is a sublimable substance in the sublimation point 25.4 ℃ Sublimation at room temperature is discharged into the gas causing various problems.

Ruthenium oxide, a quasi-volatile substance, is highly chemically toxic, and ruthenium oxide emitted from spent nuclear fuel processing is radioactive, causing serious problems for workers' safety. In addition, when ruthenium oxide, which is a semi-volatile material, is present in the exhaust gas, the gas is converted into an aerosol upon cooling, thereby causing clogging of the pipe, thereby degrading the performance of the exhaust gas treating equipment. Because of these various problems, ruthenium oxide should be removed as early as possible.

Therefore, the method of removing ruthenium oxide present in the exhaust gas has been studied in various angles, and the method of capturing ruthenium oxide can be roughly classified into physical and chemical methods. Physical methods include condensation by cooling or oxygen adsorbent action according to the oxidation number change of metal oxides, and chemical methods include ruthenium oxide reacted with alkaline earth metal mixture to form metal ruthenate. Forming method;

For example, U. S. Patent No. 3,819, 536 discloses a method in which an alkaline earth metal oxide is applied to a catalytic support, a halogenated ruthenium compound is penetrated therein, and heated to 800 to 1000 ° C to obtain a stable ruthenate.

U.S. Patent No. 3,835,069 discloses a method in which a non-volatile alkaline earth-ruthenate is formed when a ruthenium compound is mixed with an alkaline earth metal or a rare earth metal and heated above 1000 ° C. However, this method does not mention how to capture gaseous ruthenium compounds that have already been volatilized.

U.S. Patent No. 4,092,265 discloses a method for capturing a volatile ruthenium oxide with an alkaline earth metal, a lanthanide compound and lead oxide at 400 ° C to 1000 ° C to make a nonvolatile ruthenate.

Japanese Patent No. 5,437,847 discloses a method for recovering volatile ruthenium by contacting volatile ruthenium with an aqueous solution of formic acid to obtain a ruthenium oxide precipitate, and then separating the precipitate from formic acid.

However, in the above methods, the physical collection method is thermally unstable and re-volatile during the high temperature atmospheric condition or the high temperature solidification treatment after collection, and the chemical collection method using alkaline earth metals collects ruthenium compounds due to low collection capacity. In order to require a large amount of trapping material there is a problem such that a large amount of by-products are discharged by the reaction.

Therefore, the present inventors have tried to solve the problem of revolving after the collection and to develop a trapping material having a large collection capacity as a result of collecting using lithium, sodium, potassium, yttrium, rubidium compounds that have not been used for this purpose so far In the case that the above problems can be solved and the present invention has been completed.

Accordingly, an object of the present invention is to provide a method for removing ruthenium oxide present in exhaust gas. According to the method of the present invention, a large amount of ruthenium oxide can be collected with a small amount of trapping material, and ruthenium is collected. The compound is converted to a very stable material even at high temperatures so that recontamination is not a problem.

[Configuration and Function of Invention]

The present invention relates to a method for removing ruthenium oxide which is a toxic substance present in industrial exhaust gas, characterized by using a trapping material prepared by mixing alone or a mixture of lithium, sodium, potassium, yttrium and rubidium compounds.

The lithium, sodium, potassium, yttrium and rubidium compounds which are the collecting materials used in the present invention are preferably in the form of oxides.

Most preferred collecting materials include Li ₂ O, Na ₂ O ₂ , K ₂ O, Y ₂ O ₃ , Rb ₂ O, and the like.

The temperature at which the ruthenium oxide and the collector react is preferably 500 ° C to 1600 ° C.

The ruthenium compound present in the exhaust gas reacts with the components in the trapping material when it meets the trapping material to form the following compound.

Them the MRu ₄ O ₈ are holes randayi agent (Hollandite) structure as the claw air (pyrochlores) structure results present the X-ray diffraction analysis, Y ₂ Ru ₂ O ₇ is a pie, and KRu ₄ O ₈ and RbRu ₄ O ₈ And metal ruthenate structures such as NaRu ₂ O ₄ and Li ₂ RuO ₃ .

When ruthenium oxide is deposited using the trapping material of the present invention, the ruthenium trapping amount per kg of the trapping material is very large, 0.8 to 8.6 kg. Therefore, the large collection capacity per unit volume can remove a large amount of ruthenium compound in a small facility.

It can be seen that the material formed as a result of the above reaction is stable even at a very high temperature so that ruthenium oxide is not released again. In order to analyze the thermal stability of the yttrium oxide and lithium oxide obtained as a result of the reaction was carried out thermogravimetric analysis maintaining at least 1 hour at 1400 ℃. The results show that both yttrium oxide and lithium oxide form very stable metal ruthenates with weight loss less than 3% (see FIGS. 1a and 1b).

In addition, the trapping material may be used by molding the granular, supported, foamed or honeycomb monolithic form according to the flow conditions of the exhaust gas.

On the basis of the following examples will be described in more detail the present invention.

The following examples are merely illustrative of the present invention, but the content of the present invention is not limited by the examples.

Example 1

As a result of the reaction of the ruthenium oxide (RuO ₂ ) with the particulate Y ₂ O ₃ at 900 ° C. or more, the amount of ruthenium per kg of the collecting material was 0.89 kg. In addition, X-ray diffraction curve analysis formed a pyrochlores structure of Y ₂ Ru ₂ O ₇ .

Example 2

As a result of the reaction of the ruthenium oxide (RuO ₂ ) and the particulate Li ₂ O collector at 900 ° C. or higher, the amount of ruthenium per kg of the collector was 3.38 kg. In addition, X-ray diffraction curve analysis formed a pyrochlore structure of Li ₂ RuO ₃ .

Example 3

The ruthenium oxide (RuO ₂ ) and the trapping material consisting of particulate K ₂ O was reacted at 900 ° C. or higher. As a result, the amount of ruthenium per kg of the collecting material was 8.60 kg. In addition, X-ray diffraction curve analysis formed a Hollandite structure of KRu ₄ O ₈ .

Example 4

As a result of reacting the collecting material consisting of ruthenium oxide (RuO ₂ ) and particulate Rb ₂ O at 900 ° C. or higher, the amount of ruthenium per kg of the collecting material was 4.32 kg. In addition, X-ray diffraction curve analysis showed a hollandite structure of RbRu ₄ O ₃ .

Example 5

The ruthenium oxide (RuO ₂ ) and the trapping material consisting of particulate Na ₂ O ₂ were reacted at 900 ° C. or higher, and the ruthenium trapping amount per kg of the collecting material was 5.18 kg. In addition, X-ray diffraction curve analysis formed a metal ruthenate structure of NaRu ₂ O ₄ .

Example 6

Ruthenium oxide (RuO ₂ ) and yttrium oxide were respectively laminated on the separated alumina layer and heated at 900 ° C. or higher. RuO ₂ was sublimed and reacted with yttrium oxide in another layer. After the reaction, the yttrium oxide was taken out and analyzed, and as a result, Y ₂ Ru ₂ O ₇ was formed as in Example 1.

Example 7

Yttrium ruthenate was formed when a volatile ruthenium compound was passed through a collecting material formed by supporting yttrium oxide in a honeycomb monolithic ceramic at 800 ° C or higher.

Example 8

A yttrium ruthenate was formed as a result of passing a volatile ruthenium compound at 800 ° C. or higher through a collecting material formed by supporting yttrium oxide on a foam ceramic.

Claims (7)

A method for removing ruthenium compounds in industrial exhaust gases generated in a ruthenium-containing process using lithium, sodium, potassium, yttrium or rubidium compounds, and mixtures thereof as collectors. The method of claim 1 wherein the volatile ruthenium compound is ruthenium oxide. The method of claim 1, wherein the lithium, sodium, potassium, yttrium, rubidium compound is Li ₂ O, Na ₂ O ₂ , K ₂ O, Y ₂ O ₃ , Rb ₂ O characterized in that the ruthenium compound in the industrial exhaust gas How to remove. The method for removing ruthenium compounds in industrial exhaust gases according to claim 1, wherein the collecting material is used by being supported on a carrier such as ceramic, metal, quartz, glass, or the like. 5. The method of claim 4 wherein the carrier is in the form of a granular, foamed, honeycomb mono-combmonolith. The method of claim 1, wherein the ruthenium compound is removed in industrial exhaust gas. Use of a lithium, sodium, potassium, yttrium, rubidium compound or mixtures thereof as a volatile ruthenium compound collector.

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