JP5093687B2 - Method for concentrating platinum group catalysts from automotive exhaust gas converters - Google Patents

Description

  The present invention relates to a method for recovering and concentrating a platinum group catalyst from an automobile exhaust gas converter.

  Conventionally, an automobile exhaust gas converter has been subjected to a method in which a honeycomb structure is put in a dry smelting furnace to collect noble metal, or a noble metal is dissolved and extracted with an acid or the like. Regarding these improvement methods, several inventions are already known (see Patent Documents 1 to 3).

Japanese Patent No. 2717935 Japanese Patent No. 3839431 Japanese Patent No. 3679985

  However, since the concentration of noble metals contained in the honeycomb structure is low (about 0.1% to 0.5%) and it cannot be profitable unless it is a large-scale facility, the recycling rate is not necessarily high. It is thought that if the honeycomb structure is easily separated in advance at the particle stage and the precious metal is first concentrated, it will be easy to distribute to the market as a high-value-added metal powder. However, conventional particle separation techniques using magnetic separation, flotation, and liquid-liquid extraction cannot be successfully recovered.

An object of the present invention is to solve the above-mentioned conventional problems, and as a method for primarily concentrating noble metal from the honeycomb structure at the particle stage, a so-called particle separation technique (specific gravity sorting, magnetic separation, flotation, etc.) However , it is an object to realize a method of efficiently concentrating by a selective pulverization method using a two-stage crushing process.

  And in this invention, each crushing process can be simply performed, and collection | recovery is only a sieving, and makes it a subject to implement | achieve the technique introduced easily in small and medium-sized scrap collection business etc. .

In order to solve the above-mentioned problems, the present invention applies a compressive force or an impact force to a honeycomb structure, which is used as an automobile exhaust gas converter and is coated with an alumina layer supporting a platinum group catalyst on an inner wall surface by a crusher or a hammer. Te and carried particles primary crushing to expose the alumina layer carrying a platinum group catalyst on the outer surface, subjected to the allowed by the secondary crushing collision of particles with each other obtained by the primary crushing in water or air, primary the honeycomb structure as a base material for the particles obtained in crushed with little disruption, by stripping only alumina layer coated on the obtained particle surface in the primary crushing, than the honeycomb structure, alumina the layers were preferentially fine particles, by collecting the sieving screen only micronized alumina particles from the resulting particles by the secondary crushing, responsible to the fine alumina particles Provides a method of concentrating the platinum group catalyst from automobile exhaust converter, characterized in that the the concentration of the platinum group catalyst.

  According to the present invention, the alumina layer supporting the platinum group catalyst is exposed on the outer surface from the inner wall surface of the honeycomb structure by primary crushing, the alumina layer is peeled off by secondary crushing, and the alumina layer is preferentially made into fine particles. Since only the alumina fine particles are collected, the platinum group catalyst, which is a noble metal, can be easily and efficiently primarily concentrated from the honeycomb structure at the particle stage by simply performing the two crushing steps.

  An embodiment of a method for concentrating a platinum group catalyst from an automobile exhaust gas converter according to the present invention will be described below with reference to the drawings based on the examples.

  FIGS. 1A, 1B, and 1C are views showing an overall configuration, a cross section, and an enlarged state of a honeycomb structure of an automobile exhaust gas converter, respectively. The base material of the honeycomb structure 1 in the present embodiment is formed of cordierite, and the inner wall surface 4 of the lattice-like holes 3 of the honeycomb structure 1 formed from the cordierite base material 2 is provided on the inner wall surface 4 of the honeycomb structure 1. As shown in FIG. 1C, an alumina layer 5 is attached.

  In the present embodiment, the honeycomb structure 1 will be described on the basis that the base material is made of cordierite, but the present invention can be used even if it is made of another material. is there.

Alumina layer 5 is a platinum group catalyst are responsible lifting process of the present invention is a method for recovering and concentrating the alumina layer 5. That is, according to the present invention, the alumina layer 5 coated on the inner wall surface 4 in the hole 3 of the honeycomb structure 1 is peeled off, and only the alumina layer 5 is refined and collected by sieving, and is applied to the alumina layer 5. This is a method for concentrating and recovering the platinum group catalyst shown.

  In this specification, “concentration of the platinum group catalyst” does not increase the concentration of the platinum group catalyst itself, but recovers the alumina layer 5 supporting the platinum group catalyst from the honeycomb structure 1 to obtain the honeycomb structure. This means that the recovery rate of the platinum group catalyst relative to the total amount of the body 1 is increased.

  In the method of the present invention, it is first necessary to peel off the alumina layer 5 applied to the inner wall surface 4 in the hole 3 of the honeycomb structure 1. There are the following two methods for this purpose.

  The first method is a method of peeling off the alumina layer 5 by pouring a shot material or the like into the hole 3 and causing it to collide. The first method in which a shot material or the like is poured into the hole 3 and collides and is scraped off is a powerful method, but the fine particle shot material is small enough for the shot material or the like to enter the hole 3 and collide evenly with the alumina layer 5. Then, since the mass is small and the collision force is small, the peeling effect is low.

  In addition, this first method requires not only a new separation process between the separated alumina layer 5 and the fine particle shot material, but also the fine particle shot material remains in the recovered alumina layer 5 so that it is recovered. This leads to an increase in cost due to a reduction in the quality of the product and a reduction in the reuse rate of the fine particle shot material.

  In the second method, as the primary crushing, the honeycomb structure 1 composed of the cordierite base material 2 is broken to some extent, and each inner wall forming each of the many honeycomb holes 3 of the honeycomb structure 1 becomes one particle. In this way, after the alumina layer 5 is exposed on the outer surface of the particles, the cordierite particles collide with each other as secondary crushing, and the alumina layer 5 is peeled off. The one particle is a particle having a particle diameter of several millimeters. In the present specification, the one particle is obtained by crushing the cordierite base material 2 having the alumina layer 5 on the inner wall surface 4. To tell.

  Thus, in the second method in which the honeycomb structure 1 is broken to some extent and each inner wall constitutes one particle (cordierite particle), the crushing process has two stages, but the first stage crushing (primary crushing) ) Can be achieved relatively easily with hammering, compression with a press, or a commercially available crusher mainly composed of compression force or impact force.

  The second stage crushing (secondary crushing) may be performed dry (in the air), but since alumina is pulverized during crushing, operation in water is advantageous for rapid recovery. By scrubbing with stirring blades in water, the primary crushed cordierite particles gently collide with each other, and the cordierite particles are hardly destroyed and the alumina layer 5 exposed on the outer surface is removed. It can be easily peeled off.

  The particles of the alumina layer 5 thus peeled mainly have a size of the order of several tens of μm, and can be easily separated from the cordierite particles of the mm order by sieving. The second method is adopted in the method of the present invention.

  Hereinafter, the method of the present invention will be described in more detail. In the method of the present invention, first, the honeycomb structure 1 is primarily crushed by hitting with a hammer, compressing with a press, or impacting with a commercially available crusher such as a jaw crusher mainly using a compressive force or impact force. (See FIG. 2 (a)).

  By this primary crushing, the honeycomb structure 1 is destroyed so as to be crushed while the compressive force or impact force is released to the cavities of the honeycomb structure 1, so that the inner walls 4 of the numerous holes 3 of the honeycomb structure 1 are cordier. It isolates as light particle 6 (refer to Drawing 2 (a)-(c)). As a result, the alumina layer 5 coated on the inner wall surfaces 4 of the numerous holes 3 of the honeycomb structure 1 is exposed on the outer surface of the cordierite particles 6 obtained by the primary crushing of the honeycomb structure 1.

  Thereafter, secondary crushing of the primary crushed particles is performed. For example, a secondary crusher 7 as shown in FIG. 3 is used. In this secondary crusher 7, cordierite particles 6 (primary crush particles) and water are put into a cylindrical water tank 9 provided with a baffle plate 8 that easily disturbs the flow of water, and the directions of the blades are different from each other. Cordierite particles 6 obtained by primary crushing by a so-called scrubber device in which a single impeller 10, 11 is inserted and the upper impeller 10 feeds water downward and the lower impeller 11 sends water upward by rotation. Encourage collisions.

  By this collision, the alumina layer 5 is stripped from the cordierite particles 6 as alumina fine particles.

  In FIG. 3, a screen (sieving) 12 is provided in the water tank 9, and the alumina fine particles having a particle size of less than a certain particle size (for example, 45 μm or less) quickly pass through the mesh of the screen 12, and the lower alumina particle collecting pocket 13 has a structure of collecting.

  However, the screen may be implemented in a separate process after the secondary crushing. In this case, after the secondary crushing is completed by stirring for a certain time, the secondary crushed material is sieved, for example, with a screen having a mesh size of 45 μm, and the alumina fine particles falling below the screen through the mesh are collected. As a result, the platinum group catalyst can be recovered in a concentrated state with respect to the entire amount of the honeycomb structure 1 although it is supported on the alumina fine particles.

FIG. 4 is a diagram showing test results demonstrating the effect of the method of the present invention, and shows an example of the composition of a product of 45 μm or less recovered by the method of the present invention. Specifically, FIG. 4 shows the secondary crushing time and what percentage of each of the alumina layer 5 and the cordierite base material 2 is reduced to 45 μm or less by crushing. In the figure, “platinum group possession” is an error in “platinum group support” and should be read as such.

  As shown in FIG. 4, the proportion of alumina that became 45 μm or less during the crushing time of 5 minutes to 60 minutes was 37.3% to 68.8%, whereas cordierite was 2.3%. % To 6.4%, and the ratio of alumina being 45 μm or less was 10 to 16 times that of cordierite.

  Originally, cordierite is present about five times as much as alumina, so when comparing the platinum group concentration in the untreated honeycomb structure 1 with the platinum group concentration relative to the alumina particle group of 45 μm or less after treatment, Concentration of at least 4-5 times is possible.

  The best mode of the method for concentrating a platinum group catalyst from an automobile exhaust gas converter according to the present invention has been described based on the embodiments. However, the present invention is not limited to such embodiments, and It goes without saying that there are various embodiments within the scope of the technical matter described.

  Since the method of the present invention is configured as described above, it is considered that the method of the present invention can be applied to other recycling technology fields besides recovering and concentrating the platinum group catalyst from the automobile exhaust gas converter.

It is a figure explaining the honeycomb structure made into object in the Example of the method of concentrating a platinum group catalyst from the automobile exhaust gas converter concerning the present invention, and (a), (b), and (c) are respectively honeycomb structure bodies. It is a figure which shows the whole structure, a cross section, and its enlarged state. It is a figure explaining the process of the Example of the method of concentrating a platinum group catalyst from the automobile exhaust gas converter which concerns on this invention, (a) shows the state which applies the crushing force to a honeycomb structure, (b) is the primary crushing (C) is a figure which shows the enlarged view of the cordierite particle | grains which are primary crushed materials. It is a figure explaining the secondary crusher used by the secondary crushing in the Example of the method of concentrating a platinum group catalyst from the motor vehicle exhaust gas converter which concerns on this invention. It is a figure which shows the test result which demonstrates the effect by the method of concentrating a platinum group catalyst from the motor vehicle exhaust gas converter which concerns on this invention.

Explanation of symbols

1 Honeycomb structure
2 Cordierite base material
3 Holes in honeycomb structure 4 Inner wall surface
5 Alumina layer
6 Cordierite particles 7 Secondary crusher 8 Baffle plate 9 Cylindrical water tank 10, 11 Impeller
12 Screen 13 Particle collection pocket

Claims (1)

The platinum group is used as an automobile exhaust gas converter, and the honeycomb structure with an inner wall coated with an alumina layer carrying a platinum group catalyst is subjected to primary crushing by applying a compressive force or impact force with a crusher or a hammer to form particles. Exposing the alumina layer carrying the catalyst on the outer surface;
The particles obtained by the primary crushing collide with each other in water or in air to perform the secondary crushing, and the primary crushing is performed without almost destroying the honeycomb structure which is the base material of the particles obtained by the primary crushing. By separating only the alumina layer coated on the particle surface obtained in the above, the alumina layer is preferentially made finer than the honeycomb structure ,
By recovered by sieving screen only micronized alumina particles from the resulting particles by the secondary crushing, the platinum group from automobile exhaust converter, characterized in that the concentration of the platinum group catalyst supported on alumina particles A method of concentrating the catalyst.