JPS62256931A - Method for recovering ruthenium - Google Patents

Abstract

PURPOSE:To conveniently and efficiently recover Ru from a recovered material by converting the Ru and the oxide of the base metal in the recovered material into the chlorides with gaseous chlonrine while heating the material in the presence of carbon or CO, and separating the chlorides by utilizing the difference in vapor pressure. CONSTITUTION:The recovered material contg. Ru or its oxide and the oxide of the base metal is mixed with carbon powder, the mixture 1 is charged in a chloride forming vessel 4, and gaseous Cl2 is introduced from an inlet pipe 5 and the bottom of the vessel 4 through glass fiber 3 while heating the material by an electric furnace 2. Consequently, the Ru and its oxide and the oxide of the base metal are converted into the chlorides. The heating temp. is controlled to a temp. higher than the b.p. of the chloride of the base metal, or preferably to 400-1,200 deg.C. As a result, the chloride of the base material is evaporated and separated due to the difference in vapor pressure, and recovered in a collection tank 7 through a cooling pipe 6. Meanwhile, the Ru chloride is decomposed by reducing the Cl2 partial pressure to form metallic Ru, and Ru is recovered.

Description

Detailed Description of the Invention (Industrial Field of Application) The method of the present invention involves carrying out a chlorination reaction of ruthenium or ruthenium oxide and a base metal oxide and volatilization separation of the base metal chloride in a reaction part. This relates to a method for recovering ruthenium.

(Conventional technology and its problems) In recent years, inert metal electrodes and oxidation catalysts in which a ruthenium oxide film is provided on a metal oxide substrate such as titanium oxide, cobalt oxide, copper oxide, tin oxide, alumina, or silica have been developed. It is used in large quantities as an insoluble electrode in various fields of electrochemistry, especially in the salt electrolysis industry. Furthermore, electronic materials in which titanium oxide or the like is coated with ruthenium are widely used.

Such metal electrodes and catalysts have a fairly long lifespan, but when the ruthenium oxide coating gradually wears out and becomes less active during use and cannot maintain a certain level of performance, it is necessary to replace them with new ones. It is necessary to replace it with an electrode, etc. In such used metal electrodes, an amount of expensive ruthenium remains in the coating, and it is industrially important to recover and effectively utilize this.

Conventionally, Japanese Patent Application Laid-Open No. 51-6 is related to this type of technology.
No. 8493 discloses a method for solubilizing a poorly soluble substance containing ruthenium or its compounds, and JP-A-51-68499 discloses a method for recovering ruthenium by treating a sparingly soluble substance containing ruthenium or its compounds. There is. However, these methods require complicated and time-consuming processes for the alkali molten salt treatment and oxidizing solution melting steps for the peeled material. In addition, large-scale high-temperature heating equipment is required to melt the base metal oxide, and when separating the platinum group metal and base metal,
The base metal oxide is precipitated and the efficiency is poor, so it cannot be said to be an industrially optimal method for recovering platinum group metals such as ruthenium.

(Object of the Invention) The present invention was made in view of the above circumstances, and its object is to provide a method for conveniently and efficiently recovering ruthenium from a recovered material containing ruthenium or its oxide and a base metal oxide. It is about providing.

(Structure of the Invention) In a method for recovering ruthenium, the present invention involves heating a recovered material containing ruthenium or its oxide and a base metal oxide in the presence of carbon or carbon monoxide while flowing chlorine to oxidize the base metal. The method is characterized by converting ruthenium and ruthenium or its oxide into chloride, volatilizing the base metal chloride with high vapor pressure, and recovering ruthenium through separation.

Regarding chlorides, when the recovered material containing ruthenium or its oxide and the base metal oxide is heated in the presence of carbon or carbon monoxide while flowing chlorine, the ruthenium or its oxide and the base metal oxide will be converted to chloride. .

Since the vapor pressure of the commonly used base metal chloride is considerably higher than that of ruthenium chloride, it can be easily carried out of the reaction system as a gas phase. The temperature of the reaction part is preferably 600°C or higher. If the temperature is lower than this, it may take a long time, chloridation may not be completed completely, and it becomes difficult to carry the base metal chloride out of the reaction system as a gas phase.

Here, the temperature of the reaction part is preferably 600° C. or higher, but if the chloride reaction is exothermic, even if the heating temperature is lower than 600° C., it is possible to maintain the temperature at 600° C. or higher due to the reaction heat.

However, if the heating temperature is less than 400° C., a chloride reaction occurs and no heat generation can be expected.

Further, at temperatures higher than 1200°C, it becomes difficult to suppress the dissociation reaction of ruthenium even if the chlorine pressure is increased, and expensive high-temperature equipment is required.

The reason for heating in the presence of carbon or carbon monoxide is to promote the conversion of metal oxides into chlorides.

The properties of ruthenium and typical chlorides of the base metal are as follows.

RuCff, vapor pressure 0.059*nl! g/5
86°C〃〃0.777 DragonHg/727°C ANCβ3 Sublimation point 182.7°CT r Cl
a Boiling point 136.4°C ZrC7!4 331°C TaC, 242°C 34C#4 57.57°C S n Cl a # 114.1
Examples and conventional examples will be explained with reference to the drawings below.

(Example) 3.5 kg of titanium dioxide, 200 g of ruthenium dioxide,
1.05 kg of carbon powder was mixed, and as shown in the figure, this mixture 1 was placed in a chloride container 4 equipped with a glass fiber 3 at the bottom, and the chloride container 4 was heated to 600°C using an electric furnace 2, and chlorine gas was added. Chlorine gas introduction pipe 5 to 31/min
By flowing, the base metal oxide was converted into chloride and evaporated, which was liquefied through a cooling pipe 6 and transferred to a base metal chloride collection tank 7.

After continuing this for 9 hours, the remaining material was taken out, the material was reduced with hydrogen, carbon powder and unreacted materials were separated by specific gravity separation, and metal ruthenium powder was recovered.The purity of metal ruthenium was recovered at over 99%. The rate was over 99%.

(Conventional example) Titanium dioxide 36.7kg, ruthenium dioxide 4.0k
800° using KOHtK'N○3
When melted at C, KOH58.4kg, KNO36
, 1 kir, and the recovery rate of ruthenium was 90%.

As is clear from the above embodiments and conventional examples, the recovery efficiency of the present invention is 99% or more, whereas it is as low as 90% in the conventional example. Further, the conventional method requires complicated and long-time processing such as a molten salt treatment step and an acidic solution dissolution step.

Although carbon powder and chlorine gas were used in the above embodiments, a mixed gas of chlorine gas and carbon monoxide may also be used.

(Effects of the Invention) As described in detail above, according to the present invention, ruthenium can be separated and recovered from a metal base oxide more efficiently than the conventional method, and it is possible to separate and recover ruthenium from the metal base oxide without requiring the multi-stage wet treatment process as in the conventional method. Since it is not necessary, it is economical and can be recovered in a short time.

[Brief explanation of drawings]

The figure is a schematic diagram of a recovery device used in the ruthenium recovery method of the present invention.

Claims (3)

[Claims] (1) Ruthenium or its oxide and the base metal oxide are converted to chloride by flowing chlorine gas while heating the recovered material containing ruthenium or its oxide and the base metal oxide in the presence of carbon or carbon monoxide. A method for recovering ruthenium characterized by separating the ruthenium using the vapor pressure difference between the two. (2) The method according to claim 1, wherein the heating temperature is higher than the boiling point of the base metal chloride. (3) The method according to claim 1 or 2, wherein the heating temperature is 400 to 1200°C.