JPH07216467A - Method for recovering platinum-group metal from spent automobile catalyst by concentration - Google Patents

Abstract

PURPOSE:To efficiently separate and concentrate a platinum-group metal by adding lime and coke to a spent automobile catalyst contg. an iron family metal with alumina, etc., as a carrier, melting the mixture and recovering a magnetic powder from the self-collapsed powder slag. CONSTITUTION:A spent catalyst used for purifying automobile exhaust gas carrying platinum-group metals with alumina and cordierite as the carrier contains the iron and nickel resulted from the exhaust gas or released when the spent catalyst is separated from a case contg. the spent catalyst. Lime and coke are added to the spent catalyst, the mixture is melted in an inert atmosphere and slowly cooled to generate a self-collapsible slag, and a magnetic powder is recovered from the self-collapsed slag by magnetic separation. By this method, the platinum-group metal utilized as a catalyst is absorbed in iron family metals and concentrated, and the purpose is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for concentrating and recovering platinum group metals from used spent catalysts for purifying exhaust gas of automobiles in which platinum group elements are supported on alumina or cordierite as a carrier.

[0002]

2. Description of the Related Art A method for concentrating and recovering platinum group metal from an automobile waste catalyst is roughly classified into a dry method and a wet method. In both the dry method and the wet method, since the waste catalyst is hardly soluble,
It is necessary to use a melting point lowering agent or a highly corrosive agent. Moreover, since the content of platinum group metal contained in the waste catalyst is about 1500 ppm in the entire platinum group, it is necessary to use an absorbent to concentrate it in the absorbent.

When copper is used as the absorbent, the melting temperature can be considerably lowered, the slag is less corrosive, and the reducing condition is relatively weak, so that the possibility of reducing silica can be reduced.
However, cordierite tends to form a viscous slag that makes it difficult to separate the metal and the slag, and thus the separation is not good unless the melting temperature is raised.

When iron is used as the absorbent, if carbon is used to allow the presence of metallic iron as the absorbent, the melting temperature is high, so that part of the silica in the cordierite is reduced to form high silicon iron. This alloy is extremely insoluble in acids, which makes it difficult to produce platinum group metal concentrates. When the melt is settled and separated into a slag phase and a metal phase, the difference in specific gravity is large, so the phase separation is good, but in order to improve the recovery rate of the platinum group metal, it is necessary to perform sufficient phase separation. is there.

As a method of absorbing a platinum group metal into a metal matrix, there are a plasma melting method and an electric furnace melting method, but the platinum group metal is recovered from the recovered metal by a wet method because of the separability of the platinum group metal. However, iron alloys that have absorbed platinum group metals require time and effort to be powdered by shotting or atomization so that they can be rapidly leached.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for concentrating and recovering a platinum group metal from an automobile waste catalyst more efficiently and cheaply than ever before.

[0007]

According to the present invention, lime and coke are added to an automobile waste catalyst containing an iron group metal with alumina or cordierite as a carrier, melted in an inert atmosphere, and then slowly cooled. It is a method for concentrating and recovering platinum group metals from an automobile waste catalyst, which produces magnetic powder from magnetic powder that self-disintegrates by generating disintegratable slag.

[0008]

The used waste catalyst for purifying exhaust gas from automobiles, which has a platinum group element supported on alumina or cordierite as a carrier, can be used as a waste catalyst derived from exhaust gas or from a case where the waste catalyst is retained. It contains iron and nickel that are mixed in during separation. In the present invention, the platinum group metal used as a catalyst is absorbed in the iron group metal and concentrated.

The content of the iron group metal contained in the waste catalyst is, for example, about 1.3% by weight, but the amount of the platinum group metal contained in the waste catalyst is about 1500 ppm in total of the platinum group metal. It can be sufficiently absorbed by the iron group metal contained in the waste catalyst.

The reason for adding lime to the waste catalyst as a raw material is to lower the melting point of the waste catalyst and to generate self-disintegrating slag due to the difference in the shrinkage rate of crystals caused by slow cooling. When it is gradually cooled from the molten state to a temperature lower than about 300 ° C, it becomes self-disintegrating. The addition amount of lime is about 50 to 100 parts by weight with respect to 100 parts by weight of the spent catalyst, and the melting point can be lowered. When the slowly cooled slag is left in the atmosphere, 90% or more of it collapses to a size of -100 mesh.

The coke absorbs the platinum group metal by reducing the iron group metal in the waste catalyst into a metal state and bringing the metal state into the metal state. The necessary amount of the reducing agent may be calculated from the analysis results of the raw materials and added so that the amount becomes 1 equivalent or more.

The melting is carried out in an electric furnace or the like, but in order to reduce the iron group metal, it is necessary to melt in an inert gas having an oxygen concentration of 5% by volume.

The self-disintegrating slag thus obtained was examined for the presence of a platinum group metal by EPMA and WDX.
An iron group (Fe, Ni) metal alloy containing a platinum group metal has a substantially spherical shape and a particle size of about 10 to 1000 μm, and this alloy contains about 10 to 20% by weight of the platinum group metal. .

[0014]

【Example】

Example 1 1500 ppm (Pt = 1000 p) of platinum group metal in total
pm, Pd = 300ppm, Rh = 200ppm), Fe
4000 g of honeycomb or bead-shaped automobile waste catalyst made of alumina or cordierite containing 1.3% by weight is crushed, and 78% by weight of quicklime is added to the amount of waste catalyst.
(3120g) and 1.8% of coke against the amount of waste catalyst
Weight% (72 g) was added and mixed. This mixture was put into a black smoke crucible and 153 in a nitrogen gas having an oxygen concentration of 5% by volume.
Melted at 0 ° C. for 3 hours. The melt was gradually cooled to 400 ° C., taken out of the furnace and left for about 10 minutes. The slag spontaneously disintegrated and about 90% or more became powder of -100 mesh.

This powder was sieved to remove 2000 g of -100 mesh, and passed through a 920 Oersted solenoid electromagnetic separator for 5 seconds to separate into a magnetic substance (1) and a non-magnetic substance (a). . The magnetic substance (1) was further subjected to magnetic separation, and separated into a magnetic separation concentrate which was the magnetic substance (2) and a cleaning non-magnetic substance which was a non-magnetic substance. One of the non-magnetic substances (a) was further subjected to magnetic separation, and separated into a scavenging magnetic substance which was the magnetic substance (3) and a non-magnetic substance. The results are shown in Table 1.

[0016]

[Table 1] (wt%) Weight (g) Fe Al ₂ O ₃ Platinum group metal partition ratio Magnetic separation concentrate 40.0 35.5 12.3 3.500 90.0 Cleaning non-magnetic substance 8.4 0.22 23.8 0.095 0.5 Scavenging Magnetic substance 13.6 1.86 20.5 0.588 5.0 Non-magnetic substance 1938.0 0.035 25.3 0.0037 4.5 Raw material 2000.0 0.76 25.0 0.08 100.0

Example 2 The same -100 mesh powder as in Example 1 (2000 g) was taken and subjected to wet magnetic separation in the same manner to separate into a magnetic substance (1) and a non-magnetic substance (a). The non-magnetic material (a) was again subjected to wet magnetic separation to be separated into a magnetic material (2) and a non-magnetic material. Magnetic material (1)
Then, wet magnetic separation was repeated in the same manner as in (2) and (3) to separate magnetic separation concentrate (3) and a cleaning nonmagnetic material. The results are shown in Table 2.

[0018]

[Table 2] (wt%) Weight (g) Fe Al ₂ O ₃ Platinum group metal partition ratio Magnetic separation concentrate 23.9 59.00 9.21 6.276 93.0 Cleaning non-magnetic substance 8.6 3.53 22.8 0.372 2.0 Non-magnetic material 1967.5 0.04 25.2 0.0041 5.0 Raw material 2000.0 0.76 25.0 0.08 100.0 Magnetic separation concentrate and cleaning Non-magnetic The total platinum group metal recovery rate was 95% by weight.

Magnetic separation concentrates and scavenging magnetic materials in Table 1,
The magnetic separation concentrate and the cleaning non-magnetic material in Table 2 are sent to the platinum group metal recovery by a wet process, and the non-magnetic material in Table 1 and the non-magnetic material in Table 2 are sent to a refining furnace for reprocessing.

[0020]

According to the method of the present invention, most platinum group metals can be separated and concentrated from an automobile waste catalyst simply and inexpensively.

Claims (3)

[Claims] 1. A lime and coke are added to an automobile waste catalyst containing an iron group metal using alumina or cordierite as a carrier and melted in an inert atmosphere, followed by gradual cooling to form a self-disintegrating slag. A method for concentrating and recovering a platinum group metal from an automobile waste catalyst, in which magnetic powder is recovered from disintegrated powder slag by magnetic separation. 2. The method for concentrating and recovering a platinum group metal from an automobile waste catalyst according to claim 1, wherein 50 to 100 parts by weight of lime is added to 100 parts by weight of the automobile waste catalyst. 3. The molten slag is melted at 300 ° C.
The method for concentrating and recovering a platinum group metal from an automobile waste catalyst according to claim 1 or 2, wherein the method is gradually cooled to the above low temperature.