JP3380262B2 - Waste catalyst treatment method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste catalyst containing a noble metal,
In particular, the present invention relates to the recovery of precious metals such as Pt, Pd, and Rh contained in spent catalysts generated in the automobile industry or the petrochemical industry, and more specifically, characterized in that melting and electrolysis are performed under specific conditions. Regarding the processing method. 2. Description of the Related Art Heretofore, the following methods have been known as means for recovering noble metals (mainly Pt, Pd, Rh, hereinafter referred to as PGM) from spent catalysts containing noble metals generated in the automobile or petrochemical industries. ing. [0003] The waste catalyst is put into a smelting furnace (electric furnace, reverberatory furnace, flash furnace, etc.) and melted, and PG is mixed in a base metal such as copper or lead.
A metal plate enriched with M is made, and electrolysis is performed using the metal plate as an anode to deposit an electrodeposited metal on the cathode, and generate an anode slime containing PGM below the anode. The precious metal was collected by collecting the anode slime from the bottom of the battery case and treating it separately. [0004] In this method, since it is usually aimed to obtain a high-quality electrodeposited metal on the cathode, the cathode current density is reduced to 1%.
It is essential to operate within the range of 70-260 A / m ² , and at the same time, the PGM grade in the PGM-enriched anode
It was necessary to control it to 5,000 ppm or less. In addition, the PGM concentration grade in the anode is limited as described above, and continuous discharge of slime was not possible. Therefore, in order to recover precious metals on a profitable basis, it is necessary to increase the number of battery tanks considerably. Not only is the initial equipment cost enormous, but there is also a technical problem that the concentration of precious metals is low and the anode must have a long electrolytic life.
It was difficult to shorten the residence time of the PGM in the battery case. As a result, there was a major economic problem such as an increase in the interest rate on residence. [0005] As described above, the recovery of PGM by the conventional method requires a large capital investment, and can be said to be difficult to recover in a short period of time and high in actual yield. Did not. Therefore, there has been a demand for the development of a novel PGM recovery method which is inexpensive as compared with the conventional method and can be recovered in a short period of time with a high yield. Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, have found that the above objects can be achieved by performing high current density electrolysis using a diaphragm electrolytic cell. It has been found that the method according to the invention can be developed. That is, the present invention provides Pt, Pd and R
h, by treating a waste catalyst containing at least one noble metal selected from the group consisting of copper or lead for noble metal enrichment in a smelting furnace, to concentrate the noble metal in the base metal to have a diameter of 10 mmφ or less. First step of forming a metal shot; using the obtained metal shot as an anode, electrolyzing at a high current density of 610 to 1020 A / m ² in a diaphragm electrolysis tank to deposit base metal particles on a cathode, A second step of generating and depositing a noble metal-containing anode slime in the compartment; continuously extracting the base metal particles deposited on the cathode and the anode slime generated on the anode to the outside by a circulating electrolytic solution flow, and extracting the base metal particles. In the smelting furnace, and subjecting the extracted anode slime to a purification step of recovering the noble metal. Be Te is to provide a method of processing spent catalyst characterized by. The method of the present invention is directed to a waste catalyst containing a noble metal as a raw material to be treated, particularly a PGM-containing waste catalyst generated in the automobile or petrochemical industry.
One major feature is that the content of PGM in the anode for electrolysis is not limited to 5,000 ppm or less as in the conventional method. [0009] The base metal material for concentration is melted and P
To concentrate GM in the electrolytic anode, CuS or P
A base metal sulfide such as bS and a flux are added and melted in a smelting furnace. The smelting furnace may be any of an electric furnace, a reverberatory furnace and a flash smelting furnace. After the PGM-containing base metal obtained by smelting is formed into a metal shot having an average particle size of 10 mm or less, the shot is continuously supplied to, for example, a cage-shaped anode, and a high current density is supplied in a diaphragm electrolytic cell. To perform electrolytic treatment. That is, by operating at a high current density of 500 to 1,500 A / m ² of the cathode, metal particles are deposited on the cathode, and a large amount of PGM-containing slime is generated on the anode in a short time. In the diaphragm electrolytic cell used in the method of the present invention, the cathode and the anode are separated by a diaphragm.
There is no fear that the granular metal powder generated on the cathode and the anode slime generated on the anode are mixed. For this reason, the metal particles deposited on the cathode are extracted out of the battery case by the circulating electrolyte flow and filtered, and then the solid is repeatedly returned to the smelting furnace to return the filtrate to the electrolytic bath. The contained anode slime is withdrawn from the system as needed with a separate circulating electrolyte stream and filtered, the solids are sent to a purification step to recover PGM, and the filtrate is returned to the electrolytic cell. Thereby, electrolysis can be continued for a long time while continuously discharging the slime containing PGM. On the other hand, since the anode is a granular metal shot, it can be continuously replenished while observing a decrease in the level in the anode basket. Hereinafter, the present invention will be described in detail with reference to embodiments. EXAMPLE A waste catalyst treatment was performed according to the flow sheet shown in FIG. That is, first, a waste catalyst generated in the automobile industry was added to an electric furnace together with copper powder and flux and melted to produce a PGM-containing copper shot having a particle diameter of 8 mm. Its quality was as shown in Table 1. [Table 1] Using 200 g of this copper shot as the anode of a membrane electrolyzer, the current density was 610, 1,02 as shown in Table 2.
When electrolysis was performed in three stages of 0 and 1,530 A / m ² , metal powder was deposited on the cathode and PGM-containing slime was generated on the anode. Their qualities were as shown in Tables 2 and 3, respectively. In this case, the composition of the electrolytic solution was Cu 10 g.
/ l, a free H ₂ SO ₄ 100g / l, the liquid supply amount to the anode and cathode was 0.1~5.0 l / cm ² · h. [Table 2] [Table 3] As for the quality of the metal particles deposited on the cathode by this electrolysis, Pd and Rh tend to increase as the current density increases. However, since these are circulated again to the smelting furnace, there is no operational problem. . That is, the cathode deposited metal was taken out of the battery case together with the circulating electrolyte flow, filtered and returned to the smelting furnace, and the filtrate was returned to the battery case. As shown in Table 3, the total PGM quality in the PGM slime was not affected by the current density. When the PGM-containing slime had accumulated to some extent, it was extracted out of the system by a circulating electrolyte stream and filtered, and the obtained anode slime was sent to a purification step to collect Pt, Pd, and Rh individually. The filtrate was returned to the battery case again. As described above, the method of the present invention does not require the operation of taking in and out the anode unlike the conventional method, so that the handling loss of the PGM can be prevented and the size of the electrolytic cell can be reduced. Equipment costs can be reduced. In addition, the anode life is short, the anode can be continuously replenished, and the slime can be continuously withdrawn from the system, so that the PGM residence time in the tank can be shortened, and the retention interest rate can be significantly increased. There is a great economic advantage that it can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a flow sheet of a method for treating a spent catalyst of the present invention.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Ogura 2015-7 Takaya, Ichikawa-shi, Chiba Pref. Tanaka Kikino Kogyo Kogyo Co., Ltd. (72) Inventor Masaei Takada 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Kosaka Smelting Co., Ltd. (56) References JP-A-57-110633 (JP, A) JP-A-61-217536 (JP, A) JP-B-49-26801 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22B 1/00-61/00 C25C 1/12-1/20

Claims (1)

(57) [Claim 1] A waste catalyst containing at least one noble metal selected from Pt, Pd and Rh in a smelting furnace together with a base metal material comprising copper or lead for concentrating noble metals. A first step of concentrating the noble metal in the base metal into a metal shot having a diameter of 10 mm or less by performing the treatment; and using the obtained metal shot as an anode in a diaphragm electrolyzer in a diaphragm electrolytic cell at a rate of 610 to 1020 A / m ² . A second step of electrolyzing at a current density to electrodeposit and deposit base metal particles on the cathode and generating and depositing a noble metal-containing anode slime in the anode compartment;
The base metal particles deposited on the cathode and the anode slime generated at the anode are each continuously withdrawn out of the system by a circulating electrolytic solution flow, and the extracted base metal particles are repeated in the smelting furnace to remove the extracted anode slime. A method for treating a spent catalyst, comprising a third step of providing a purification step of recovering the noble metal.