JPS6296322A - Recovery of ru - Google Patents

Abstract

PURPOSE:To efficiently separate and recover Ru, by passing Cl gas through a waste material of an electrode, having an RuO2 coating and used in brine electrolytic industry while heating the waste material together with C powder to convert the substrate of the electrode into a chloride. CONSTITUTION:An electrode having an Ru oxide coating on the surface of a substrate, e.g. Ti, TiO2, Co2O3, Al2O3 or SiO2, is used as an electrode used for electrolysis of brine. An electrode having the Ru oxide coating consumed and deactivated by use for a long time is replaced by a new electrode. Since expensive Ru is left in the used old electrode, the electrode is, together with an electrode substrate, e.g. Ti, made into a mixture 1 containing added carbon and put in a chlorination vessel 4. Cl gas is then fed from an inlet pipe 5 through glass fibers 3 while heating the mixture 1 at 600-1,000 deg.C in an electric furnace 2. The Ti or TiO2 in the electrode substrate is reduced into a chloride, volatilized and cooled in a cooling pipe 6, liquefied and introduced into a tank 7. Solid residual materials in the vessel 4 are separated by specific gravity into C powder and Ru to recover the Ru in good yield.

Description

Detailed Description of the Invention (Industrial Field of Application) The method of the present invention involves a chlorination reaction of Ru or Ru oxide and a base metal oxide, a dissociation reaction of Ru chloride, and a reaction of a base metal chloride in a reaction part. The present invention relates to a method for recovering Ru by performing both volatilization and separation.

(Prior art and its problems) In recent years, various insoluble metal electrodes and oxidation catalysts have been developed 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. It is used in large quantities as an insoluble electrode in the field of electrochemistry, especially in the salt electrolysis industry. Furthermore, magnetic materials and semiconductor materials in which titanium oxide or the like is coated with a platinum group metal are widely used.

Such metal electrodes and catalysts have a fairly long lifespan, but when the Ru oxide film 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. A considerable amount of expensive ruthenium still remains in the coating of these used metal electrodes, and it is industrially important to recover and utilize it effectively.

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 compound, and JP-A-51-68499 discloses a method for recovering ruthenium by treating a dissolvable substance containing ruthenium or its compound. There is. However, these methods require complicated and time-consuming processes for the alkali molten salt treatment and oxidizing solution dissolution 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 precipitates out, making it inefficient and 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 simply and efficiently recovering ruthenium from a recovered material containing Ru or its oxide and a base metal oxide. It's about doing.

(Structure of the Invention) The present invention provides a method for recovering Ru by heating a recovered material containing Ru or its oxide and a base metal oxide in the presence of carbon while flowing chlorine. Convert Ru or its oxide to chloride and immediately R
The method is characterized in that only the u chloride is dissociated into metal Ru, and then separated and recovered.

In chlorination, when the recovered material containing Ru or its oxide and base metal is mixed with carbon powder and then heated while flowing chlorine, Ru or its oxide and base metal oxide turn into chlorinated products, but Ru Above the dissociation temperature of chloride, R
When chlorine reacts with a mixture of carbon powder and the recovered material containing u or its oxide and base metal oxide, and the mixture is in excess of chlorine, chlorine reacts almost completely. , the chlorine partial pressure becomes minute. Ru chloride easily undergoes a dissociation reaction to become metal Ru. The commonly used chloride of the base metal causes a dissociation reaction and has a boiling point lower than the dissociation temperature of Ru, so it can be easily carried out of the reaction system as a gas phase.

The temperature of the reaction part is preferably 800 to 1000°C. If the temperature is lower than this, it may take a long time or the chlorination may not be completed completely.
There is a possibility that the u chloride cannot be dissociated into metal Ru and may evaporate and come out of the system. Here, the temperature of the reaction part is 800-10
00℃ is preferable, but if the chlorination reaction is an exothermic reaction, even if the heating temperature is less than 800℃, the reaction temperature
It is possible to maintain the temperature within 1000°C.

However, when the heating temperature is less than 600°C, the chlorination reaction is difficult to occur, and the resulting heat generation cannot be expected. Moreover, if the temperature is higher than 1000° C., expensive high-temperature equipment is required.

The reason for heating in the presence of carbon is to promote the substitution of metal oxides and chlorine.

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

RuC1, 24+m11g74 at dissociated chlorine pressure 450'C
389mmHgAA'C7 at 0℃! zboiling point 182.7
℃ T+Cj! a Boiling point 136.4°C ZrCl a 331°C TaC1a Boiling point 242°C 5iC (14〃 57.57°C 5nCj'4'' 114.1°C or less Examples and conventional examples will be explained with reference to the drawings.

(Example 1) 3.5 kg of titanium dioxide, 200 g of ruthenium dioxide,
1.05 kg of carbon powder was mixed and the mixture 1 was placed in a chlorination container 4 equipped with a glass fiber 3 at the bottom as shown in the figure.
The chlorination container 3 is heated to 800°C using the electric furnace 2, and chlorine gas is introduced from the chlorine gas introduction pipe 5 for 5//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 chloride collection tank 7. After this was continued for 5 hours, the remaining material was taken out and the metal Ru powder was recovered by separating the carbon powder by specific gravity separation, and the purity of the metal Ru was 99% or more and the recovery rate was also 99% or more.

(Conventional example) Titanium dioxide 36.7kg, Ruthenium dioxide 4.0
When a mixture of KOH2S and KNOZ was melted at 800°C, 4kg of KOH2S was obtained.
36.1 kg of K N O was required, 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.

(Effects of the Invention) As described in detail above, according to the present invention, Ru can be separated and recovered from the metal base oxide more efficiently than in the conventional example, and it does not require the multi-stage wet treatment process as in the conventional example. Since this method does not require the use of 300 ml, it has the advantage of being economical and can be recovered in a short period of time.

[Brief explanation of drawings]

The figure is a schematic diagram of a recovery device used in the Ru recovery method of the present invention. Applicant: Tanaka Kikinzoku Kogyo Co., Ltd. 7...1 (Spontaneous amendment to the procedure for the capture of prisoners of war) 1985/1-30th 1, Indication of the case 1985 Patent Application No. 234898 No. 2, Method for recovering the title Ru of the invention 3, Person making the amendment 4, Subject of the amendment 5, Contents of the amendment 1) After “recent years” in the fourth line of page 2 of the specification, “Titanium,
” to join. 2) Add ``Metal ya'' after ``...- etc.'' in the 5th line. 3) Correct "mo" in the 9th line to "wo". 4) Correct "magnetic material, semiconductor" in the 10th line to "electron". 5) "Platinum group metal" in the 8th line of page 3 is corrected to "ruthenium". 6) Add "water" after "base metal" on page 3, line 9. 7) Delete "platinum group metals such as" on the 10th line. 8) Correct "chlorination" in line 5 of page 4 to "chloride". 9) Delete "element" in the 8th line. 10) rRu on the 9th line to 11th line or ---
React and correct the "mixture" to "recovered product". 11) Correct "." in the 13th line to ",". 12) Add "chloride" after rRuJO on the 16th line. 13) Delete "In some cases, chlorination may not be completed completely" in the 20th line. 14) In the first line of page 5, "chlorination is complete" is corrected to "chlorination is complete". 15) Correct "chloride reaction" in the 5th line to "chloride reaction". 16) Correct "chlorination" in the 8th line to "chloride". 17) "Chlorination" on page 6, line 9 of the same page is corrected to "chlorination." 18) Correct "chlorination container 3" on the 10th line to "chloride container 4". 19) “Metal base” on page 7, line 12 of the same page is “base metal”
Correct to.

Claims (1)

[Claims] 1) In the presence of carbon, the recovered material containing Ru or its oxide and the base metal oxide is heated while flowing chlorine gas to convert the base metal oxide into chloride and evaporate and separate it. A method for recovering Ru, characterized in that: 2) The method according to claim 1, wherein the heating temperature is higher than the dissociation temperature of the Ru chloride and higher than the boiling point of the base metal chloride. 3) The method according to claim 1 or 2, wherein the heating temperature is 600°C to 1000°C.