RU2094501C1 - Method of affinated ruthenium producing - Google Patents

Abstract

FIELD: chemical technology, noble metals. SUBSTANCE: method involves reduction of ruthenium oxidized powder with a mixture of ammonia and inert gas. EFFECT: improved quality, decreased reaction time and fire hazard. 2 cl, 1 tbl

Description

 A method for producing refined ruthenium relates to the field of non-ferrous metallurgy, in particular, refining of noble metals.

In the process of refining, a pure salt of ammonium nitrosapentachlororuthenate is obtained, upon calcination of which a sponge metal is formed containing up to 5% oxygen associated with ruthenium in the form of oxide. In commodity ruthenium powders, the content of volatile impurities is allowed not more than 0.02%
From the literature [1-4] and the practice of refining production, only one method is known for producing ruthenium powder from the specified product. So, in the method adopted for the prototype [4], the final salt of ammonium nitrosopentachlororuthenate is calcined in air, partially oxidized spongy ruthenium is washed with water, boiled in acids, dried and calcined in a stream of hydrogen.

 The main disadvantages of the prototype are: a relatively high content of volatile components in the target product, a long process time, increased fire and explosion hazard.

 The aim of the invention was to remedy these disadvantages.

 This goal is achieved by the fact that in the known method for producing refined ruthenium, including thermolysis of a ruthenium salt in air and subsequent reduction of an oxidized ruthenium powder with a gaseous reactant, ammonia mixed with an inert gas is used as a reducing agent. Inert gas is used as a transport gas for ammonia, in addition, it eliminates the possibility of the formation of explosive mixtures in the recovery zone. The cheapest and most common of inert gases is nitrogen, which was used to create a reducing gas mixture with ammonia.

The essence of the method lies in the fact that when heated, as established in the course of the research, ammonia is able to reduce ruthenium from oxides, for example, by reaction (1):
3RuO ₂ + 4NH ₃ = 3Ru + 2N ₂ + 6H ₂ O
Moreover, the content of volatile impurities in the ruthenium powder reduced with ammonia is lower than after reduction with hydrogen. This is probably due to the lower adsorption on the surface of the metal ruthenium of ammonia and gaseous reaction products (1) compared with hydrogen. Literature data can testify to the validity of such a proposal (see, for example, Ref. [5], which indicates the ability of platinum metals to absorb hydrogen with the formation of sufficiently strong chemical compounds.

It is also important that when using a mixture of ammonia with nitrogen instead of hydrogen, the likelihood of an explosion during the process is significantly reduced (the explosion hazard of the hydrogen-air mixture at room temperature and atmospheric pressure is from 4 to 74% H ₂ , and ammonia-air mixtures 14.5 26.8% NH ₃ ) [6]
Example. 20 kg of ammonium nitrosopentachlororuthenate are loaded into a platinum glass and calcined in an oven until salt is completely decomposed. The resulting oxidized sponge is crushed, washed with water from impurities of sodium chloride, and boiled in hydrofluoric acid. The washed oxidized ruthenium powder is loaded into a platinum boat, placed in a cold tube furnace, into which an ammonia-nitrogen gas mixture is fed.

 An ammonia-nitrogen mixture is obtained by passing (sparging) nitrogen through a layer of concentrated aqueous ammonia solution. In this case, the resulting mixture is a nitrogen saturated with ammonia vapor.

After the air is displaced from the pipe, the heating is turned on, the charge is heated to 1100 ± 50 ^o C and kept at this temperature in a stream of ammonia-nitrogen mixture for 1 to 4 hours. Then, the heating is turned off and the furnace is cooled (without stopping the flow of ammonia-nitrogen mixture) to a temperature of 20 - 60 ^o C. After cooling, the furnace is switched to a purge with one nitrogen, and the flow of the mixture is stopped. Nitrogen is purged for 3-5 minutes. The recovered metal is discharged, crushed and analyzed for impurities, including volatile components.

 From experiments 6 7 it is seen that the replacement of the reagent-reducing agent ensures the guaranteed production of conditioned metal and a decrease in the content of volatile impurities by 2 3 times with a processing time of 2 4 hours. Reducing the duration to 1 hour (experiment 5) does not always provide a regulated content of volatile impurities in metal and is not optimal.

 The results are presented in the table.

In addition to ammonium nitrosopentachlororuthenate, the proposed method can also process chloroammonium salts of ruthenium, for example, (NH ₄ ) ₂ [RuCl ₆ ] (NH ₄ ) ₂ [RuOHCl ₅ ] and ruthenium dioxide and others.

Thus, the proposed method allows you to:
2 to 3 times reduce the content of volatile components in refined ruthenium;
reduce the recovery time of oxidized ruthenium powders by 2 3 times;
to reduce the explosion and fire hazard of the process.

Literature
1. Zvyagintsev O.E. Refining of gold, silver and platinum group metals. M. Metallurgizdat, 1945, p. 155.

 2. Zvyagintsev O.E. et al. Chemistry of ruthenium. M. Science, 1965, p. 290.

 3. Raevskaya M.V. Sokolovskaya E.M. Physicochemistry of ruthenium and its alloys. M. Moscow University, 1979, p. 35.

 4. Metallurgy of noble metals. Ed. L.V. Chernyaeva, ed. 2, M. Metallurgy, 1987, p. 414.

 5. Ginzburg S.I. et al. Guidelines for the chemical analysis of platinum metals and gold. M. Science, 1965, p. 9.

 6. Brief chemical encyclopedia, 1v.1, M. Soviet Encyclopedia, 1961, p.202.

Claims (2)

 1. A method of producing refined ruthenium, including thermolysis of a ruthenium salt in air and subsequent reduction of an oxidized ruthenium powder with a gaseous reagent, characterized in that ammonia mixed with an inert gas is used as a reagent.  2. The method according to p. 1, characterized in that nitrogen is used as an inert gas.

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