JPS6191335A - Method for recovering platinum group metal - Google Patents

Abstract

PURPOSE:To recover easily and efficiently a platinum group metal from a recovered material contg. the platinum group metal in a short period by heating the recovered material while passing chlorine in the presence of carbon and separating and recovering the formed platinum group metallic chloride. CONSTITUTION:A mixture 1 formed by mixing carbon powder with the recovered material contg. the platinum group metal or the oxide thereof and base metallic oxide is put through a mixture introducing pipe 2 into a chlorina tion vessel 3 and while the chlorine is passed therein from a gaseous chlorine introducing pipe 4, the mixture is heated to convert and evaporate the compsn. of the recovered material to chloride. The temp. in the above-mentioned heating is preferably kept at 800-1,000 deg.C. The formed vapor of the above-mentioned chloride is introduced into a capturing vessel 8 consisting of a glass vessel 8 packed with glass wool 7 and is kept at the temp. below the b. p. or decompsn. temp. of the platinum group metallic chloride and above the b. p. of the base metallic chloride by a solder bath tank 5. The platinum group metallic chloride is thus separated and recovered as the crystal having high purity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for recovering platinum group metals.

(Prior art and its problems and points) In recent years, metal oxide coatings such as ruthenium oxide have been coated on metal oxides such as titanium oxide, cobalt oxide, copper oxide, tin oxide, alumina, and silica. Insoluble metal electrodes and oxidation catalysts are used in large quantities as insoluble electrodes in various fields 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.

Although these metal electrodes and catalysts have a fairly long lifespan, the platinum group metal oxide coating gradually wears out and becomes less active during use, and when they are no longer able to maintain a certain level of performance. , it is necessary to replace it with a new electrode, etc. In such used gold bus electrodes, a surface equivalent amount of expensive platinum group metal components such as ruthenium remains in the coating, and it is important for engineering 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 the base metal, the base metal oxide precipitates, resulting in poor efficiency and This cannot be said to be a method for recovering platinum group metals such as ruthenium.

(Object of the Invention) The present invention has been made in view of the above-mentioned circumstances, and its object is to easily and efficiently produce platinum such as ruthenium from recovered materials containing platinum group metals or their oxides and base metal oxides. The object of the present invention is to provide a method for recovering group metals.

(Structure of the Invention) The present invention provides a method for recovering platinum group metals by heating a recovered material containing a platinum group metal or its oxide and a base metal oxide in the presence of carbon while flowing chlorine.
The method is characterized in that after converting the base metal oxide and the platinum group metal or its oxide into a chloride, the platinum group metal chloride is separated and recovered.

The present invention will be explained in more detail below.

The method of the present invention is divided into (1) a chlorination step and (2) a chloride separation step.

(1) In the chlorination process, the collected material containing the platinum group metal or its oxide and the base metal oxide is mixed with carbon powder and then added while flowing chlorine! and c) converting the platinum group metal or its oxide and the base metal oxide into a chloride.

The platinum group metal or its oxide and the base metal oxide are all chlorinated and evaporated. Note that not only the base metal oxide but also unoxidized base metal is chlorinated and evaporated. Heating is preferably carried out at temperatures between 800" and 100°C. At temperatures lower than this, chlorination may take a long time or may not be completed completely, and at temperatures higher than this, unnecessary This is because new high-temperature equipment will be required.

Carbon powder is essential to replace oxygen in metal oxides with chlorine.

As a result, the oxide of the platinum group metal and the base metal oxide or base metal were completely chlorinated and evaporated, and no residue was found in the reaction vessel.

The properties of typical chlorinated products of platinum group metals and base metals are as follows.

p t c l 2 435-531°C Stable in chlorine.

PtCl 4 Decomposed at 370℃.

PdC1z Sublimation and 1 decomposition at 600℃. Dissociation pressure is 92
76031 Hg at 0°C.

Ru CI 3 dissociation pressure is 24+n Hg at 450°C
, 389°C m Hg at 740°C.

I r CI 3 Stable at 100-763°C. 470
Volatizes at °C.

Decomposes to IrC'12 at 763°C.

rrcl2 dissociation pressure is 241+n Hg at 71'1℃
, 731 DragonHg at 771℃, decomposed to rrcl at 773℃.

I r CI PA! Ml! Pressure is 698℃-153
mm H' g, 799°C 771 Dragon Hg.

A I C13 boiling point 182.7℃, TaC11 boiling point 24
2℃.

TiC1, boiling point 136.4°C, S i C, I 4
Boiling point 57.57°C.

ZrC1, boiling point 331°C, 5nC14 boiling point 114.1
"c.

(2) In the chloride separation step, the platinum group metal chloride obtained in the 5-chlorination step is collected in a collection container maintained at a constant temperature. From the standpoint of collection, it is preferable to maintain the collection device at a constant temperature that is above the boiling point of the base metal chloride and below the boiling point or decomposition temperature of the platinum group metal chloride. At temperatures below the boiling point of the chlorinated base metal, the chlorinated base metal will also be collected in the collection vessel, and separation from the chlorinated platinum group gold mud will be incomplete, and the boiling point or decomposition temperature of the chlorinated platinum group metal will be incomplete. This is because, at the above temperature, collection of platinum group metal chlorides is not completed completely, and the recovery rate decreases to 1. As a result, only platinum group metal chlorides are obtained as crystals in the collection vessel.

The platinum group metal chloride thus obtained has high purity and is soluble, so it can be efficiently and easily purified.

Hereinafter, embodiments and conventional examples will be described with reference to the drawings.

(Example 1) Titanium dioxide 10.0kg, ruthenium dioxide 1.0
kg.

Mix 6.0 kg of carbon powder, put this mixture 1 into the chlorination container 3 through the mixture introduction pipe 2, and heat the container 3 to 900°C while flowing chlorine through the chlorine gas introduction pipe 4. The mixture was kept at 400°C and chlorinated for 2 hours, and one ruthenium chloride was separated and recovered.

The collection container 5 consists of a glass container 8 in which glass wool 7 is filled in a solder bath 6. No residue was found in chlorination container 2, and chlorination was completed.

The purity of the separated ruthenium chloride was 99% or higher, and the recovery rate was also 99% or higher.

(Example 2) In the same manner as in Example 1, 10 kg of alumina carrying 1% by weight of platinum was crushed and mixed with 7.2 kg of carbon powder, and this mixture 1 was introduced into the chlorination container 3 through the mixture introduction pipe 2.
The mixture was heated to 900° C. while flowing chlorine, and the collection container 5 was kept at 300° C. for 2 hours of chlorination to separate and recover platinum chloride.

The recovered material was completely chlorinated, and the purity of the separated platinum chloride was over 99%, and the recovery rate was also over 99%. (Conventional example) Titanium dioxide 36.7kg, Ruthenium dioxide 4.0k
tc mixed with KOH + KNO3 at 800℃
When melted, KOf158.4kg, KNO3
6.1 kg 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, platinum group metals can be separated and recovered from metal base oxides more efficiently than conventional methods, and in addition, it is possible to separate and recover platinum group metals from metal base oxides using a multi-stage wet method as compared to conventional methods. Since no treatment process is required, it is economical and can be recovered in a short period of time.

[Brief explanation of drawings]

Claims (1)

[Claims] 1) The base metal oxide and the platinum group metal or its oxide are produced by heating the recovered material containing the platinum group metal or its oxide and the base metal oxide in the presence of carbon while flowing chlorine. After converting into chlorinated products, the platinum group metal chlorinated products are separated,
A method for recovering platinum group metals, the method comprising: recovering platinum group metals. 2) The method according to claim 1, wherein the platinum group metal chloride is separated and recovered at a temperature below the boiling point or decomposition temperature of the platinum group metal chloride and above the boiling point of the base metal chloride. 3) Heating the recovered material under chlorine flow from 800℃ to 1000℃
The method according to claim 1 or 2, which is carried out at ℃.