KR100436448B1 - low temperature smelting processing for recycling waste automotive catalyst mixed uniformly with flux and reductant - Google Patents

Abstract

The present invention utilizes a homogeneous mixing process of flux and reducing agent to reduce precious metal elements such as platinum (Pt), palladium (Pd), and rhodium (Rh) from the waste catalyst for exhaust gas purification to be disposed of. Disclosed is a method for recovering a platinum group element from a low temperature melting process of an automobile catalyst by a homogeneous mixing process of a flux and a reducing agent melted and extracted in a temperature range.

The object of the present invention is to separate and purify a platinum group metal by melting the mixture of the waste catalyst for exhaust gas purification at low temperature by a homogeneous mixing treatment process with a flux and a reducing agent. The mixture of automobile waste catalyst carriers is melted at low temperatures to separate into copper collectors, from which the platinum group elements are recovered via conventional wet separation processes. According to the uniform mixing treatment technology of the flux and the reducing agent of the present invention, not only can the melting temperature and the melting time of the automotive waste catalyst carrier be reduced, but also a high yield of platinum group element can be recovered from the copper collector.

The present invention as described above can not only lower the melting temperature by improving the composition and melting process conditions of the conventional inefficient solvent when extracting the platinum group element from the exhaust gas purification vehicle waste catalyst by the uniform mixing process of flux and reducing agent High yields of platinum group metals can be recovered. Therefore, the platinum group metals contained in the spent catalysts, which are disposed of in large quantities every year, can be usefully separated and purified at low cost.

Description

Low temperature smelting processing for recycling waste automotive catalyst mixed uniformly with flux and reductant}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering a platinum group element from a low temperature melting process of an automotive waste catalyst by a homogeneous mixing process of a flux and a reducing agent, and in particular, an automobile waste for exhaust gas purification that is disposed by using a homogeneous mixing process of a flux and a reducing agent. The present invention relates to a method of melting and extracting noble metal elements such as platinum (Pt), palladium (Pd), and rhodium (Rh) from a catalyst at a temperature range much lower than a conventional treatment temperature.

Generally, platinum group metals such as platinum (Pt), palladium (palladium, Pd), rhodium (Rhodium, Rh), iridium (Iridium, Ir), ruthenium (Ru) and osmium (Osmium, Os) Metals (PGM) are used as raw materials for catalysts, electrical and electronics, petroleum, aviation, glass, medical and high-tech industries because of their excellent physical and chemical properties, and demand is increasing rapidly as industrial development and living standards improve. In particular, platinum, palladium, and rhodium have excellent gas adsorption properties, high melting point, and high corrosion resistance even at high temperatures, and are widely used as catalysts for oxidation and hydrogenation reactions in the petroleum and chemical industries and exhaust gas purification catalysts for automobiles. It is becoming.

However, the average annual production of platinum group metals is around 30 tons, more than 85% of which is produced in South Africa and the former Soviet Union, with only about 9% of Canada being produced in South America, the United States, Australia and Japan. Therefore, these catalysts and components are degraded over time, and eventually discarded at the end of their lifetime, but especially because platinum group metals are expensive, it is economically beneficial to recover and resource them. As for not only recycling finite resources but also solving environmental problems caused by wastes in terms of environment, it will be very meaningful. However, in Korea, the research on recycling method of automobile waste catalyst has not progressed very much. Especially, technology for extracting and refining platinum group element contained in automobile waste catalyst is still insufficient. In fact, they are forced to export to other countries and suffer a lot of economic losses in the country.

Due to the serious air pollution caused by the increase in the supply of automobiles, the regulation of automobile exhaust gas has been enforced since 1975, and in advanced countries such as the United States and Japan, automobile exhaust gas purification catalytic converters are obliged to be attached to automobiles. _x , SO _x , CO, HC) As the regulatory standards are strengthened, the need for high-capacity catalysts using carriers containing higher concentrations of three-way catalyst noble metals than existing catalysts and the new demand for oxidation catalysts required for diesel vehicles, etc. As a result, the demand for platinum group metals used as automotive catalysts is expected to skyrocket. Currently, three-way catalysts containing Rh and Pt or Pd are present in almost all passenger cars. Korea has been in operation since 1987, and as the supply of automobiles increases, the demand for platinum group metals for automobile exhaust gas purification catalysts is steadily increasing. Automotive exhaust gas purification catalysts include platinum, palladium and rhodium in alumina, cordierite and silicon carbide (SiC) carriers, and about 0.4-3.5 g of precious metal is used per exhaust gas purification catalyst converter. Automobile exhaust gas purification catalysts use a granular or monolithic ceramic support as a carrier. The granular type has a simple manufacturing method, but is gradually becoming a single body due to problems such as exhaust purification ability and high back pressure immediately after starting the engine. Platinum group metal scraps and wastes of various types and forms are not effectively treated due to their weak separation and purification technology.

Currently, various methods are used to extract white metal elements from automotive waste catalysts, but wet methods that directly leach precious metal elements with acids or alkaline solutions are increasingly being specified worldwide due to the possibility of environmental problems such as water pollution. Instead, the slag is formed by melting the spent catalyst catalyst and the trapping agent together in a plasma or arc furnace capable of high temperature heating above 2000 ° C, and the platinum group elements are collected by the trapping agent in the crude metal state, and then refined by wet separation process. Dry dissolution is adopted in most countries.

The precious metal dry dissolution method, which is one of the extraction methods of platinum group metals, is a method in which scrap or waste is melted together with a solvent at a high temperature, and then the platinum group metal is collected and recovered as a collecting metal. Can handle scrap. In addition, the precious metal dry dissolution method is important to reduce the loss of platinum group elements to be extracted from the molten exhaust gas waste catalyst, it is very important to maintain proper slag composition for this purpose. Since the melting point of cordierite, which is a spent catalyst carrier, and a high viscosity, it is difficult to deal with waste catalysts in the case of automobile waste catalysts by the noble metal dry dissolution method, it is necessary to find a method for solving them. Considering the influence of particle size during melting, it is important to determine the grinding conditions because the smaller the particle size, the better the melting. Considering the effects of flux addition, melting point and viscosity can be adjusted according to the addition of flux, so it is necessary to consider the effects and economics of flux.

As described above, the wet method and the general dry dissolution method, which are the conventional methods for recovering the platinum group element from the automobile waste catalyst, have many problems, and thus, the study on the improved recovery method is urgently required.

An object of the present invention is to separate and purify a platinum group metal by melting at a low temperature a mixture of an automobile waste catalyst for purification of exhaust gas by a uniform mixing treatment process with a flux and a reducing agent.

In order to overcome the problems of the conventional method for recovering the platinum group element from the automotive waste catalyst, the chemical composition of the flux and the reducing agent added together with the automobile waste catalyst carrier to the melting furnace is controlled and the waste catalyst carrier is carried out through a uniform mixing process. The melting temperature of the mixture was greatly lowered, and it was confirmed that the recovery rate of the platinum group metal contained in the trapping metal could be increased, thereby completing the present invention.

The present invention relates to a method for recovering an automobile waste catalyst in which platinum (Pt), palladium (Pd), and rhodium (Rh) are mixed, fluorite, borax, soda ash and soda ash as reducing agents. It is characterized by recovering the platinum group metal by melting homogeneously and uniformly with copper, which is a collecting agent, in order to melt at low temperature to separate the collecting metal from slag.

Specific examples of the automotive waste catalyst include a ceramic cordierite (cordierite, 2Al ₂ O _3, 5SiO _2, 2MgO) carrier of high surface area honey comb type containing 0.1 to 5 wt% platinum group element as a catalyst. Is mainly used. In the present invention, first, the above-mentioned automotive waste catalyst carrier is mixed with copper as a collecting agent, wheat as a reducing agent, and fluorite as a flux at a first ratio, and then the particle diameter of the powder mixture of the automobile waste catalyst is about 100 by dry ball milling. Mix and grind until it becomes below mesh. Secondly, borax and soda ash, which are another fluxing agent, are mixed uniformly by the same dry ball milling process. In the above process, the mixture powder of the automotive waste catalyst uniformly mixed with the flux and the reducing agent is subjected to a step of adding the powder to the melting furnace. In this case, the reason for limiting the diameter of the mixture powder of the crushed automobile waste catalyst to 100 mesh or less is that the melting conditions such as melting temperature and melting time and slag properties after melting are largely changed according to the particle size of the mixture powder. This is because the recovery rate also greatly affects.

The temperature of the melting furnace is meltable at 1000 ~ 1700 ℃, particularly preferably 1100 ~ 1300 ℃, the flowability of the slag under such conditions is easy and the extraction of the platinum group element is easy.

The process of recovering the copper trapping the platinum group element contained in the exhaust gas vehicle waste catalyst through the melting process, and then the process of extracting the platinum group element through the wet separation process or electrolytic process of the collected metal copper is conventional wet refining According to the process technology.

According to the present invention, as described above, the platinum group metal can be more efficiently extracted from the exhaust gas automobile catalyst through a low temperature melting base process, so that waste can be easily resourceed, and pollution prevention and economic recovery of platinum group elements can be achieved. In order to provide a method that can be, a preferred embodiment was carried out according to the above-described manufacturing process.

Representative process chart of the present invention

An embodiment of the present invention is as follows.

<Example 1>

In the electric melting furnace, an experiment was performed to separate the platinum group element from the main domestic exhaust gas vehicle waste catalyst by the low temperature melting process method of the present invention.

In the first mixing and crushing process, the components added together with the exhaust gas vehicle waste catalyst carrier are weight percent of the automobile waste catalyst carrier, which is about 40 wt% copper as a collecting agent, 5 wt% wheat as reducing agent, and 5 wt% fluorite as flux. It is put into a ball mill, and homogeneous mixing and grinding are performed by a dry ball milling process for 1-2 hours.

In the second mixing and grinding process, a ball mill is used as a mixture of 100 wt% borax and 100 wt% soda ash as another flux to the mixture powder of the exhaust gas vehicle catalyst having undergone the mixing and grinding process as a weight percent of the primary mixture powder. The mixture was added to the mixture, and then mixed and ground in a dry ball milling process for 1-2 hours.

The mixture of automobile catalyst catalysts homogeneously mixed by the above-mentioned sequential homogeneous mixing and pulverization process is introduced into a melting furnace and melted at a temperature of 1200 ° C. for at least 2 hours to melt and separate the copper collector in the slag which has been completely melted. The platinum group element was extracted from the separated copper collector through a conventional wet separation process.

As a result, the recovered amount of platinum (Pt) per kilogram of automotive waste catalyst sample was 1.501g, the recovery amount of palladium (Pd) was 0.0395g, the recovery amount of rhodium (Rh) was 0.1185g. Therefore, the general value of the total value of the platinum group recovery amount generally obtained through the platinum group recovery method through the conventional melting method is 1000 ppm (= total amount of the platinum group metal recovered / 1 kg carrier sample), the flux and the reducing agent in the present invention When the platinum group element was recovered by homogeneous mixing and pulverization by adjusting the type and amount of ethylene to a low temperature melting process and recovering the platinum group element, the total value of the platinum group recovery amount was about 1659 ppm, which greatly exceeds the existing results. Is showing.

Tables 1 and 2 show the material component ratios of the primary and secondary mixing and grinding processes employed in this <Example 1>.

Automotive waste catalyst carrier (cordierite) Copper Fluorite Wheat Chemical formula 2Al ₂ O ₃ · 3SiO ₂ · 2MgO Cu CaF ₂ Weight percent (wt%) 100 40 5 5

Table 1.Material component composition ratio in the first mixing and grinding process of <Example 1>

Primary Car Waste Catalyst Mixture Borax Soda ash (sodium carbonate) Chemical formula Na ₂ B ₄ O ₇ 10 H ₂ O Na ₂ CO ₃ Weight percent (wt%) 100 50 50

Table 2. Composition of Material Components in Secondary Mixing and Grinding Process of <Example 1>

<Example 2>

After the first mixing and pulverizing process with the same material mixing composition as in Example 1, after performing the second mixing and pulverizing process using 100 wt% by weight using only borax as a flux, the collecting metal body after melting by the same melting method Was prepared, and the platinum group element was extracted through the wet separation process and the electrolysis process.

Primary Car Waste Catalyst Mixture Borax Soda ash (sodium carbonate) Chemical formula Na ₂ B ₄ O ₇ 10 H ₂ O Na ₂ CO ₃ Weight percent (wt%) 100 100 0

Table 3. Composition of Material Components in Secondary Mixing and Grinding Process for <Example 2>

As a result, the recovered amount of platinum (Pt) per kilogram of automotive waste catalyst sample was 1.407g, the recovery amount of palladium (Pd) was 0.0382g, the recovery amount of rhodium (Rh) was 0.1163g.

As shown in the experimental results of the above embodiments, even when comparing the extraction rate of the platinum group element compared to the conventional melting process conditions, the first and second sequential homogeneous mixing and grinding process of reducing wheat and flux fluorspar By mixing uniformly, borax and soda ash in an appropriate ratio and injecting it into the smelter, it was possible to drastically lower the melting temperature of the automobile waste catalyst carrier, and the slag fluidity after the melting facilitated the smooth tapping and the separation of the platinum group elements. Considering the actual operation aspects it was confirmed that the case of Example 1 is the best melting conditions through the platinum group recovery.

As can be seen through the above embodiment, the present invention is melted by improving the composition and melting process conditions of the conventional inefficient solvent when extracting the platinum group element from the exhaust gas purification vehicle waste catalyst by the uniform mixing process of the flux and the reducing agent In addition to lowering the temperature, high yields of platinum group metals can be recovered. Therefore, there is a useful effect such that the platinum group metal contained in the automobile waste catalyst, which is disposed of in large quantities every year, can be separately purified and recycled at low cost.

Claims (5)

Primary mixing and pulverization by mixing and pulverizing by adding 5 wt% wheat as reducing agent, 5 wt% fluorspar as flux, and 40 wt% copper as collecting agent, and mixing to pulverize the particles to 100 mesh or less. Fair, A secondary mixing and grinding step of mixing and grinding and homogenizing by adding 50 wt% of borax and soda ash, which are fluxes, in a weight percentage of the mixture of automobile waste catalysts obtained in the above-described primary mixing and grinding step; The homogeneous mixture powder of the automobile waste catalyst carrier produced by the above secondary mixing / crushing process was introduced into the melting furnace, and the copper collectors were separated by tapping and separating the copper collector from the highly fluidized slag melted at a temperature of 1200 ° C., where it A method for recovering a platinum group element from a low temperature melting process of an automobile waste catalyst by a uniform mixing treatment of a flux and a reducing agent, characterized by comprising a step of extracting a platinum group metal. delete delete The method of claim 1, A method for recovering a platinum group element from a low temperature melting process of an automotive waste catalyst by a uniform mixing treatment of a flux and a reducing agent, wherein the final mixture powder is fine powder of 100 mesh or less in the above secondary mixing and grinding process. delete