JPH02301527A - Method for recovering platinum family metal - Google Patents

Abstract

PURPOSE:To simply and efficiently separate and recover a Pt family metal from a metal oxide carrier by mixing a recovery contg. the metal and the carrier with a specified amt. of CaF2, feeding gaseous chlorine to the recovery under heating to a specified temp., converting the Pt family metal into chloride and vaporizing this chloride. CONSTITUTION:When a Pt family metal is recovered from a recovered catalyst supporting the Pt family metal and/or the oxide thereof on a metal oxide carrier such as alumina or silica, CaF2 or NaF is added to the recovered catalyst by 0.5-10wt.% and gaseous chlorine is fed to the catalyst under heating to 600-1,200 deg.C. The Pt family metal and/or the oxide thereof is converted into chloride and this chloride is vaporized and separated from the metal oxide carrier. The Pt family metal can be efficiently and simply recovered in a short time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention involves mixing CaF2 or NaF into a recovered material containing a platinum group metal and/or its oxide and a base metal oxide, and heating the mixture with chlorine gas. The present invention relates to a method for recovering platinum group metals by carrying out a chlorination reaction of platinum group metals and/or their oxides by flowing , and separating the platinum group metals by volatilization from the base metal oxide.

(Prior art and its problems) Catalysts in which platinum group metals and/or their oxides are supported on metal oxide substrates such as alumina, silica, and silconium have been used in the purification of automobile exhaust gas, electrolytic electrodes, and petrochemical industries. It is used in large quantities for various purposes.

When the activity of the platinum group metal in such a catalyst decreases during use and a certain level of performance cannot be maintained, it is necessary to replace it with a new catalyst.

A considerable amount of expensive platinum group metals still remain in these used materials, and it is industrially important to recover and utilize them effectively.

Conventionally, methods for recovering platinum group metals include dissolution methods using acids, aqua regia, etc., but these methods require a long multi-stage wet treatment in the dissolution step.

Also, a large amount of water is required for cleaning the base metal oxide.
Furthermore, when separating the platinum group metal from the base metal, there are problems such as precipitation of base metal hydroxide, resulting in extremely low recovery efficiency, making the recovery method unsuitable for industrial use.

(Object of the invention) The present invention has been made to solve the above problems, and its object is to provide a base metal oxide with a platinum group metal and/or
Another object of the present invention is to provide a method for simply and efficiently recovering platinum group metals from a material that retains their oxides.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the method for recovering platinum group metals of the present invention includes adding Ca F 2 or The method is characterized in that by mixing NaF and flowing chlorine gas while heating, the platinum group metal and/or its oxide is converted into chloride and separated by volatilization.

As a method for retaining platinum group gold R and/or its oxide in the base metal oxide, in the case of r-Flumina where the base metal oxide itself has a sufficient unit surface area as a catalyst, it is possible to directly hold the platinum group gold R and/or its oxide. If the base metal oxide itself does not have a sufficient unit surface area, γ
- A method is adopted in which a catalytically active layer such as alumina is provided and the catalyst is held there.

When the recovery operation according to the method of the present invention is performed, the catalytically active layer of T-alumina that holds the platinum group also gradually reacts as the platinum group volatilizes.

When CaF2 or NaF is mixed, the volatilization of the T-alumina catalyst active layer and the platinum group is promoted, but the effect is not clear, but it is thought to be due to a type of catalytic effect.

Gradually reacting the catalyst active layer holding the platinum group is considered to be a factor in efficiently volatilizing the platinum group.

The reaction in the catalytic active layer is a reaction in which aluminum chloride is produced by the chlorination reaction of T-alumina, and can be expressed as follows.

Afz O+(r)+3(12 CaF2, NaF (catalyst) AIICfl, + 3/202 The aluminum chloride produced by this reaction is 182,
It has a sublimation point of 7°C and can be easily separated from platinum group chlorides.

The amount of CaF or NaF added is preferably in the range of 0.5% to 10%.

At a value lower than 0.5%, no effect of addition is observed and the reaction is similar to that without addition.

On the other hand, if it is added in an amount of 10% or more, the reaction will be inhibited and the effect of the addition will be weakened.

(Example) Examples and conventional examples of the platinum group recovery method of the present invention will be described.

First, an example of the platinum group recovery method of the present invention will be described.

(1) PtO,
A catalyst for automobile exhaust gas purification carrying Pd 0.059%, Pd 0.052%, and Rh 0.028% was crushed and purified using a sieve.
10μm~420μm, 420μm~210μm1
It was classified into three types, 210 μm to 90 μm. The respective percentages were 44.3%, 23.1%, and 301%, with 2.4% having a diameter of 90 μm or less.

500g of catalyst of each particle size is mixed with 5% CaF, and as shown in the figure, the reaction tube (inner tube) 2 is filled with silica sand 5 for heating chlorine gas, and above it is a porous material for the purpose of dispersing chlorine gas. This recovered material 1 was put into a reactor in which a ceramic 4 and a ceramic filter 3 were set.

Thereafter, it was loaded into a reaction tube (outer tube) 10.

The reaction tube (outer tube) 10 had a scavenger layer at the top, and was filled with B a Cl 2 .

While heating to 1000° C. in an electric furnace (A) 7, chlorine gas was flowed through a chlorine gas blowing pipe 6 to carry out a chlorination reaction in a fluidized bed.

The flow rate of chlorine in the flow reaction of catalysts of each particle size is 710 μm ~
420μm, 8 f/min, 420μm~210%
m.

4 f/min, 210% m to 90 μm, 11
! It took 7 minutes.

The reaction gas was passed through two layers of B a Cl filled in a collector 9 heated to 830° C. in an electric furnace (B) 8 to collect platinum group chlorides.

After carrying out this reaction for 3 hours, the B
a CIt 2 was taken out, dissolved in water, and reduced and recovered with S'BH. The recovery rates of P, t, Pd, and Rh were as shown in Table 1 below.

Table-1 (2) T-alumina pellets for catalyst (average particle size 2mm)
A gas reforming catalyst carrying 1.91% Ru was crushed and collected with a size of 710 μm to 210 μm using a sieve.

10% of NaF was added to 400 g of this classified material, and this recovered material 1 was set in the same manner as in Example (1).

The collector layer 9 was filled with KCl.

While heating to 850° C. with an electric furnace (A) 7, chlorine gas was flowed through the chlorine gas blowing pipe 6 at a rate of 6β/min to perform a fluid reaction.

The reaction gas was heated to 730° C. in an electric furnace (B) 8 and passed through a KCji layer filled with a collector 9 to collect Ru chloride.

After carrying out this reaction for 3 hours, the KC
When Ru was taken out, dissolved in water, reduced with SBH, and recovered, the recovery rate of Ru was 97.4%.

(Conventional Example) (1) PtO,
A catalyst for automobile exhaust gas purification carrying 0.059%, PdO, 0.52%, and Rh 0.028% was crushed and sieved (similar to Example 1) as shown in the figure (using the same apparatus as Example 1). When Pt, Pd, and Rh were recovered by reacting for 3 hours under the same conditions as in Example (1), the recovery rates of each were as shown in Table 2 below.

(Left below) Table 2: 5280.25g of the same catalyst as in (2) and (1) in 6N hydrochloric acid.
Immerse it in a solution, heat it to 60°C, blow chlorine gas into it and dissolve the platinum group. After this reaction for 4 hours, remove the hydrochloric acid solution by filtration, and precipitate the platinum group as sulfide with H2S. When recovered using this method, Pt, Pd,
The recovery rate of Rh was 93.1% 94.3% 80
．． It was 2%.

In order to increase the recovery rate in this recovery, a problem arose in that the amount of washing liquid used during filtration increased significantly.

(Effects of the Invention) As can be seen from the above explanation, according to the method of the present invention, platinum group metals can be separated and recovered from the base metal oxide very efficiently, and the conventional wet filtration and washing steps are not required. It has the excellent effect of being able to be easily recovered in a short time because it does not cause any damage.

[Brief explanation of drawings]

The figure shows an example of the platinum group metal recovery method of the present invention.

Claims (1)

[Claims] (1) Add 0.5 to 1 of CaF_2 or NaF to the recovered material containing the platinum group metal and/or its oxide and the base metal oxide.
0 wt% is mixed and heated to 600°C to 1200°C while flowing chlorine gas to convert the platinum group metal and/or its oxide into chloride and volatilize it, separating it from the base metal oxide,
1. A method for collecting platinum group metals, the method comprising: recovering platinum group metals;