JPS6179736A - Recovering method of platinum group metal - Google Patents

Abstract

PURPOSE:To recover platinum group metals easily and efficiently by heating the recovered substance contg. platinum group metals or their oxides and the oxides of a base metal with hydrofluoric acid to dissolve the oxides of the base metal in the hydrofluoric acid. CONSTITUTION:The recovered substance contg. platinum group metals or their oxides and the oxides of a base metal is added to hydrofluoric acid, and the mixture is heated to 40-60 deg.C. The oxides of the base metal dissolve in the hydrofluoric acid, but the platinum group metals or their oxides do not dissolve in it. By filtering this hydrofluoric acid soln. through activated carbon, the platinum group metals or their oxides can be recovered by separation.

Description

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

(Conventional wave IV technology and its problems) In recent years, titanium oxide, cobalt oxide, copper oxide, tin oxide,
Insoluble metal electrodes and oxidation catalysts, which are coated with a platinum group metal oxide such as ruthenium oxide on a metal oxide substrate such as alumina or silica, are used in various fields of electrochemistry, especially in the salt electrolysis industry. It is used in large quantities as. Also, magnetic materials such as titanium oxide coated with platinum group metals.

Semiconductor materials 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 mud electrodes, an amount of expensive platinum group metal components such as 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 compound, and JP-A-5168499 discloses a method for recovering ruthenium by treating a sparingly soluble substance containing ruthenium or its compound. However, these methods require complicated and time-consuming processes for the alkali molten salt treatment and acid solution dissolution process for the peeled material. In addition, large-scale high-temperature heating equipment is required to melt the base metal oxide, and furthermore, when separating the platinum group metal and the base metal, the base metal oxide precipitates, resulting in poor efficiency and an unsuitable method for industrial use. 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 a platinum group metal by heating a recovered material containing a platinum group metal or its oxide and a base metal oxide with hydrofluoric acid to convert the base metal oxide into hydrogen fluoride. The method is characterized in that platinum group metals or their oxides are separated and recovered by dissolving them in acid.

The present invention will be explained in more detail below.

The method of the present invention is divided into fl) a hydrofluoric acid heating step, and (2) a melt separation step.

(11 In the hydrofluoric acid heating step, the recovered material containing the platinum group metal or its oxide and the base metal oxide is heated with hydrofluoric acid to dissolve the base metal oxide into the hydrofluoric acid. Platinum group metals or their oxides do not react with or dissolve in hydrofluoric acid.In addition to base metal oxides, there are unoxidized base metals that dissolve in hydrofluoric acid. The heating is preferably carried out at a relatively low temperature of 40°C to 60°C. At higher temperatures, HF will volatilize and the concentration of hydrofluoric acid will decrease; at lower temperatures, HF will dissolve in the hydrofluoric acid. This is because it may take a long time or the melting may not be completed completely.As a result, the base metal oxide or base metal is completely dissolved in the hydrofluoric acid.

This step replaces the precipitation of the platinum group metal or its oxide with a clear hydrofluoric acid solution.

(2) In the solution separation step, the hydrofluoric acid solution containing the precipitate of the platinum group metal or its oxide obtained in the hydrofluoric acid heating step is filtered through activated carbon to easily remove the insoluble platinum group metal. Or its oxide can be separated and recovered.

Conventional recovery methods can be applied to recovery of platinum group metals. When an insoluble platinum group metal is separated, it may be dissolved in aqua regia or the like, or it may be cast as it is. Additionally, if the platinum group metal oxide is separated, it can be purified using conventional alkali molten salts. In this case, since it does not contain base metals such as titanium oxide, the equipment can be small and it can be purified to a high degree of purity.

Examples and conventional examples will be described below.

(Example 1) 60 kg of water is added to 120 kg of 46% hydrofluoric acid to dilute it.

After heating to around 50° C., while maintaining this temperature, a mixture of 36.7 kg of titanium dioxide and 4.0 kg of ruthenium dioxide was gradually added and dissolved. After the solution was cooled to room temperature, only ruthenium dioxide was separated and recovered by filtration using activated carbon. All of the titanium dioxide was dissolved, and the ruthenium dioxide content in the filtered residue was 99% or more. To melt this ruthenium dioxide with KOH + KNO3, 6.8 kg of KOH and 36.1 kg of KNO are used.
kg, and the recovery rate of ruthenium was over 99%.

(Example 2) 15 kg of alumina supporting 1% by weight of platinum was crushed,
This was dissolved in hydrofluoric acid in the same manner as in Example 1, and platinum was separated and recovered. In this case, as in Example 1, all the alumina was dissolved, and the platinum content in the filtered residue was 9.
It was over 9%.

(Conventional example) Titanium dioxide 36.7 kg, ruthenium dioxide 4.
800 kg mixed using KOH+KNOa
Tatokoro melted at °C, KOH58.4kg, KNO
36.1 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%, while that of the conventional example is as low as 90%.

In addition, in the conventional example, it was necessary to increase the size of the melting apparatus at high temperature or to perform many repeated operations, which required a lot of time and effort for the equipment.

(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 moreover, platinum group metals can be separated and recovered from a large molten salt as compared to conventional methods. There is an advantage that it can be recovered economically because it does not require the use of a dissolving device.

Claims (1)

[Scope of Claims] 1) A recovered material containing a platinum group metal or its oxide and a base metal oxide is heated with hydrofluoric acid to dissolve the base metal oxide in the hydrofluoric acid, and the platinum group metal or A method for recovering platinum group metals, characterized by separating and recovering oxides. 2) The method according to claim 1, wherein the hydrofluoric acid is heated at 40°C to 60°C.