JP2003301225A - Method for recovering noble metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering noble metals from an organic material containing the noble metals, in a high yield and without forming hazardous materials. <P>SOLUTION: The method for recovering the noble metals comprises heating and carbonizing the organic material containing the noble metals to form a carbonized material containing carbon of 0.5 wt.% or more, heating and melting the carbonized material together with flux mainly consisting of silica, alumina, and a calcium compound to separate them into a metallic layer having absorbed the noble metals and a flux layer, further oxidizing the provided metallic layer containing the noble metals to concentrate the noble metals, and refining the noble metals from the concentrated metallic layer containing the noble metals. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for recovering a noble metal from an organic substance containing a noble metal. More specifically, it describes an organic substance and a noble metal containing a trace amount of a noble metal catalyst used in the chemical industry. Including thermoplastic resins, thermosetting resins, ion-exchange resins and activated carbon, organic polymer materials such as noble metal-containing circuit boards that compose electric and electronic parts, ceramic catalysts containing noble metals and organic substances, and more It is a recovery method that prevents the generation of loss from waste materials and recovers precious metals in high yields, and that does not produce harmful substances and is in harmony with the environment.

[0002]

With the development of the chemical industry, supported catalyst systems,
Noble metal catalysts such as complex catalyst systems have been widely used in synthetic reactions. Further, with the development of the information industry, the amount of electronic devices used has been increasing, and along with this, the amount of organic substances containing trace amounts of precious metals has been rapidly increasing. Since the precious metal is an expensive substance, it is necessary to recover it from these organic substances, but since it is contained in a large amount of organic matter, it is difficult to efficiently recover the precious metal unless the organic matter is removed.

Further, a large amount of waste liquid in which noble metal ions and the like are mixed in the reaction liquid is also generated. In the case of recovering precious metals from these wastes, conventionally, a method of burning and removing organic substances contained in large amounts in these wastes has been conventionally used. However, since the ash produced by incineration has a low apparent specific gravity, the ratio of scattering into the combustion gas and loss is high,
It was a major factor that lowered the recovery rate of precious metals.
Furthermore, environmental pollution of dioxins generated during incineration is a major obstacle.

Further, when these organic substances containing a noble metal are incinerated, the noble metal is oxidized and contained in the ash as an oxide. When recovering a noble metal from ash, a wet method in which it is dissolved in an acid or the like is used as a conventional method, but it is difficult to sufficiently increase the recovery rate by this method because the solubility of the noble metal oxide is poor. Furthermore, in the ash produced by incineration, the precious metal is confined in a strong carbon matrix and is difficult to elute, which is a factor of lowering the recovery rate.

In addition, a method of treating an ion-exchange resin or activated carbon containing a noble metal at 1300 to 1400 ° C. by adding oxides of silicon, aluminum, magnesium and copper oxide, and a melting point lowering agent for lowering the melting point at the time of melting. Has also been proposed (JP-A-4-317423). However, when treating ion exchange resin or activated carbon containing a large amount of organic matter, if you put it in a high temperature furnace, the organic matter will decompose and a large amount of organic gas will be generated rapidly, resulting in explosion, fire, and generation of toxic gas. , Problems such as odor generation often occur. Therefore, it is practically difficult to immediately treat an organic substance containing a large amount of volatile components at a high temperature.

[0006]

In view of the above problems, it is possible to prevent the generation of loss in the process of recovering precious metals as much as possible, and to recover precious metals in high yield, and to produce harmless substances and to be in harmony with the environment. The present invention intends to develop and provide a recovery method that is applicable to a complex mixture of organic substances containing many kinds of precious metals.

[0007]

Means for Solving the Problems The inventors of the present invention prevent the loss of precious metal from an organic substance containing a precious metal as much as possible,
The method for removing the organic matter was thoroughly studied. As a result, by heating and carbonizing the organic material under specific conditions, foaming during heating and carbonization is prevented, oxidation of the precious metal is suppressed, and the precious metal is trapped in the carbide, resulting in loss of precious metal. However, it has been found that

Further, in order to concentrate a trace amount of noble metal contained in the carbide, the carbide is heated and melted together with a flux composed mainly of silica, alumina, and a calcium compound to separate a noble metal absorbed metal layer and a flux layer. Then, it has been found that the precious metal can be concentrated in the metal layer by preventing the loss of the precious metal by further oxidizing the separated metal layer having absorbed the precious metal to further oxidize the precious metal. Further, it was confirmed that the noble metal can be recovered in a high yield by purifying the metal layer having an increased concentration of the noble metal content and recovering the noble metal, and the present invention was accomplished based on these findings.

The method of the present invention is applicable to liquid, solid or semi-solid organic compounds, thermoplastic resins, thermosetting resins, ion exchange resins, activated carbon, organic polymer materials such as recovery substrates for electric and electronic parts. It can be applied to organic substances containing a wide range of wastes containing a trace amount of precious metals, such as organic substance-containing ceramics catalysts, and can recover precious metals in high yield.

That is, an organic substance containing a noble metal is heated and carbonized to generate a carbide having a carbon content of 0.5% by weight or more, and the carbide is heated together with a flux composed mainly of silica, alumina and a calcium compound. It melts and separates into a metal layer in which the noble metal is absorbed and a flux layer. A method for recovering a noble metal, comprising further oxidizing the obtained noble metal-containing metal layer to concentrate the noble metal, and then purifying the noble metal from the concentrated noble metal-containing metal layer.

Further, in the heating / carbonization step, carbonization is carried out at a temperature rising rate of 600 ° C./hour or less up to 200 ° C. and 200 ° C./hour or less from 200 to 450 ° C., and a carbon content of 5 wt% or more. The present invention also includes a method of obtaining Also, in this step, sodium as a carbonization promoter,
It is also possible to add 10 to 500% by weight of at least one component selected from the group consisting of potassium, calcium hydroxide, hydroxide, carbonate and sulfuric acid, carbon, silica, alumina to the organic substance. Included in the present invention. Alternatively, the present invention also includes a method of adding a metal oxide together with a flux component to a carbide obtained from an organic substance containing a noble metal catalyst and / or a waste thereof and heating and melting the same.

Furthermore, in the step of adding a metal oxide together with a flux component to a carbide containing a noble metal and heating and melting, the metal oxide is copper oxide, and the temperature for heating and melting and phase separation is from 1100 ° C to 1500 ° C. A certain method and a method for purifying a noble metal from a concentrated noble metal-containing metal layer,
The present invention also includes a method of recovering a noble metal, which is a wet method using an acid.

Here, the noble metal usually refers to a white metal element containing gold, silver and palladium, rhodium and platinum, but is particularly expensive and is often contained in the organic material referred to in the present invention, rhenium and ruthenium. Iridium and the like are also targets for recovery of the present invention. In addition, carbides include organic substances that include metals and ceramics at 450 ° C.
Of the products obtained by the above heating / carbonization treatment, inorganic substances such as these metals and ceramics naturally remain, but the residues containing these and carbon are collectively referred to. Hereinafter, the present invention will be described in detail.

The organic substances containing these noble metals include liquid, solid and semi-solid organic compounds, thermoplastic resins, thermosetting resins, ion exchange resins, activated carbon, circuit boards constituting electric and electronic parts, etc. Organic polymer materials, ceramic catalysts containing organic substances, etc. are included, and their forms are also diverse. In addition, the content of the noble metal is often very small, and a large amount of organic substances are accumulated in the deteriorated noble metal-supported catalyst and the like, but the noble metal recovery method of the present invention can be applied to a wide range of these raw materials. .

Since a liquid organic substance in which a noble metal ion or the like is dissolved in an organic solvent or water generally has a low concentration of the noble metal, it is necessary to evaporate and concentrate the solvent to recover the noble metal. However, the liquid substance is likely to be bumped at the time of evaporation, and the precious metal is scattered along with the droplets and becomes a loss, so that the yield is remarkably reduced. The same applies to the case where the liquid matter is sprayed and burned to recover the ash. In the resinous material, the organic component is melted and decomposed by heating to foam, or a sublimable decomposition product is generated and precious metal is scattered along with these volatile components and becomes a loss, resulting in a decrease in yield. Trouble such as blockage is likely to occur.

Therefore, in the precious metal recovery method of the present invention, a carbonization promoter is first added to an organic substance containing a precious metal to obtain a solid or semi-solid substance. As a matter of course, when the solvent is contained in a large amount, it is also effective to add the carbonization promoter after removing the solvent within the economically reasonable range. That is, after the heat treatment, a carbonization promoter may be added so that a solid or semi-solid product can be obtained. The addition of a carbonization promoter improves the melting point and carbonization yield, and prevents foaming, making it possible to carbonize / decompose even polyester-based waste, which was previously difficult to oilize, and to convert noble metals to carbides. Since it is fixed inside, the recovery rate of precious metals is significantly improved.

The carbonization accelerator is a component added to increase the decomposition temperature of organic substances and accelerate the carbonization rate, and hydroxides, oxides such as sodium, potassium and calcium,
Carbonate, sulfuric acid, and porous solids such as activated carbon, carbon, silica and alumina can be used. Further, these components can be used either as powders or molded products. The amount of carbonization promoter added is 10 per 100 parts by weight of organic substances.
The amount is preferably up to 500 parts by weight, and can be appropriately determined depending on the acid equivalent and composition of the organic substance.

In addition, even solids such as ceramics and activated carbon,
When a volatile organic substance is contained, a carbonization promoter can be added to increase the recovery rate of precious metals. The method of adding the carbonization promoter is not particularly limited, but it is made into a powder and mixed, or after mixing while crushing the organic substance, the pelletizer is added.
After granulating using a commercially available device such as the above, heating / carbonization treatment can be performed.

In the heating / carbonization process of the present invention,
An organic substance containing a noble metal is heated and carbonized to obtain a carbide. At this time, it is preferable to treat under a specific condition in order to prevent loss of the noble metal. Further, depending on the organic substance, air may be used, but the oxygen concentration in the atmosphere gas is at least the oxygen concentration in the atmosphere or less, and preferably 0.
It is preferable to adjust it to be 1% or less. The atmospheric gas depends on the nature and amount of the organic substance used, but it is simply achieved by not introducing new air during or after the introduction of these organic substances into the heating / carbonization apparatus. It Further, the combustion exhaust gas easily has an oxygen concentration of 0.1%, and can be suitably used in the present invention.

The organic matter contained in the organic substance is at least 0.5% by weight in the carbide due to reaction, decomposition, volatilization, etc.
It is necessary to treat the above carbon so that it remains, and it is preferable that 5% by weight or more remains. As the heating / carbonizing apparatus, any one of a rotary kiln, a vertical shaft kiln, a batch type furnace, or an apparatus combining them is particularly preferable. This is because it is easy to control the oxygen concentration during heating / carbonization and to set temperature conditions.

Regarding the conditions of the heating / carbonization treatment, the temperature rising rate is 600 ° C./hour or less up to 200 ° C.
Up to 50 ° C, it is preferable to set the heating rate at 200 ° C / hour or less. By raising the temperature in the low temperature region at a low speed, it is possible to prevent foaming and entrainment and scattering of precious metals. Also, by setting the maximum temperature of heating / carbonization to 800 ° C or less, excessive development of the higher-order structure of carbon can be prevented, and the noble metal can be efficiently absorbed in the metal layer in the next step. More preferably, 200 ° C
The rate of thermal decomposition up to 400 ℃ / hour to 40 ℃ / hour, the halogen contained in the organic substance,
Atoms such as oxygen and nitrogen can be removed. Next 450
The carbonization treatment step of heating up to ℃ is a step for further heating the pyrolyzed organic matter to promote carbonization, and the temperature rising rate of this treatment step is preferably 200 ℃ / hour to 50 ℃ / hour. Thereby, the content of the volatile component contained in the carbide can be reduced to 5% or less.

When the temperature raising conditions in the pyrolysis and carbonization treatment steps are rapidly heated beyond the scope of the present invention,
It cannot be used because the loss of precious metals is often large. The lower limit of the temperature rising rate is not limited,
It only needs to be economically feasible. Further, by adding a predetermined amount of the carbonization promoter in this step, the carbide can be obtained more efficiently. Further, when the transfer to the next step is necessary, it is preferable to perform heat treatment so that the solid state or the semi-solid state is obtained.

Furthermore, it is economical that the final heating / carbonization temperature is low, and it is not necessary to raise the temperature. The temperature may be 450 to 800 ° C, which is a temperature sufficient for the noble metal to be incorporated into carbon, and the maximum temperature and the holding time may be adjusted so that 0.5% by weight or more of carbon remains in the carbide.

Due to the melting point increasing effect of the addition of the carbonization accelerator, the decomposition and carbonization of the organic substance gradually progresses, so that the decomposition gas generation rate is low, and the decomposition gas generation amount is much smaller than that during combustion. Further, since the precious metal is confined in the carbide, the amount of scattering with the decomposition gas is small, and the residual rate of the precious metal is 90% or more, and in most cases it reaches 99% or more. In order to further increase the residual rate of the noble metal in the carbonization step, it is more preferable to pelletize the raw material into a uniform shape.

The carbonized material having a carbon content of 0.5% or more obtained by decomposing and carbonizing the organic matter in the heating / carbonizing step is heated to a high temperature in a system containing a flux composed mainly of silica, alumina and a calcium compound. Then, it is melted and separated into a metal layer containing a noble metal and a flux layer made of an oxide. In the present invention, a composition whose main components are silica, alumina, and a calcium compound is preferable in order to increase the recovery rate of noble metals.

Incomplete separation of the noble metal layer and the flux component,
When the absorption of the noble metal into the noble metal layer is insufficient, a reducing agent may be added depending on the situation. As the reducing agent, a carbon material is preferable because it is simple and inexpensive. In particular, in the present invention, since a carbide containing carbon is obtained by heat treatment, it is not necessary to further add a reducing agent, and the consumption of the carbon electrode normally used in the melting heating furnace is reduced. Further, when the obtained carbide is heated together with the flux component to separate it into a metal layer and a flux layer, if the metal content is insufficient and the separation is difficult, a metal oxide should be added to eliminate the separation failure. You can also

The metal oxides include copper, iron, lead, zinc,
Although oxides of tin, antimony and the like can be used, copper, iron or a mixture of copper and iron is preferable in terms of price and stability. In the present invention, since the main components of the flux are silica, alumina, and a calcium compound, by adding copper oxide as a metal oxide, the melt separation temperature from 1100
The temperature can be as low as 1500 ° C., the separability of the metal layer and the slag layer, the extraction efficiency of the precious metal into the metallic copper layer are improved, and the purification of the precious metal by acid dissolution becomes easy as described later.

In this step, in order to lower the melting point of the slag layer and improve separation, borax, silica stone,
Coal, limestone, fluorite, shale, calcia, etc. can be used. In addition, the carbide is crushed and these flux components are added and mixed, and the mixture is heated to 1300 to 1500 ° C. in a melting furnace for a sufficient time of 3 to 3 times for the noble metal to be absorbed by the metal layer.
A method of holding and melting for 10 hours is preferable. As a result, a glass-like oxide slag layer and a reduced metal layer are separated, and a molten layer of a metal containing a noble metal is settled due to a difference in specific gravity and separated into an upper glass-like oxide slag layer.
Further metals can be added to enhance the separability.

Subsequently, the upper molten slag layer is discharged from the melting furnace, and the lower molten metal layer is introduced into an oxidation furnace to oxidize the metal. The oxidation treatment is for further concentrating the noble metal contained in the molten metal layer, and an oxygen gas or a gas containing oxygen (hereinafter referred to as an oxygen-containing gas) is sprayed or blown onto the molten metal to form a metal oxide. This is the step of generating. At this time, even if the unreacted noble metal-containing carbide remains in the metal layer, it is oxidized and decomposed by this oxidation treatment, and the contained noble metal moves to the metal layer.

The oxide layer produced by oxidation is separated into an upper layer and a molten metal layer inside the oxidation furnace due to the difference in specific gravity from the molten metal layer. During this layer separation, the noble metal taken into the oxide layer by the oxidation operation also moves to the molten metal layer, and a metal layer in which the noble metal is concentrated is formed. At this time, elements other than noble metals such as iron, chromium, and aluminum hardly migrate to this metal layer, but become an oxide and migrate to the oxide layer.

The molten metal layer thus obtained is cast and cooled, and then used as a raw material for collecting noble metal, and purified by a conventional method such as electrolytic refining or acid dissolution to obtain a noble metal. When copper, iron, or a mixture of copper and iron is used as the metal oxide, a method of dissolving in an inorganic acid such as aqua regia or hydrochloric acid monochlorine is preferred. Further, since the oxide layer separated in the oxidation step contains a large amount of metal oxide and a trace amount of the precious metal element still remains, it is preferable to circulate and use the raw material for precious metal recovery.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described more specifically with reference to Examples.

(Example 1) A crushed material of a used mobile phone including an electronic circuit board (about 20 mm in size) was placed in a combustion exhaust gas atmosphere with an oxygen concentration of 0.1% or less using a rotary kiln.
Heated and carbonized. The heating rate is 3 up to 200 ° C.
The treatment was carried out at 00 ° C / hour and at 200 to 450 ° C at 100 ° C / hour.
The carbonization yield at this time was 20.1%, the main component of the carbide was copper, the carbon content was 36.3%, and the gold was 117%.
It contained 5ppm, silver 5535ppm and palladium 265ppm.

To 100 parts by weight of this carbide, 80 parts by weight of alumina, 200 parts by weight of silica and 180 parts by weight of calcium oxide were added as a flux component, and the mixture was heated to 1450 ° C. in a heating furnace and held for 4 hours to give a mixture. It melted and separated into a layer consisting of metallic copper containing a noble metal and slag.

The metal copper layer containing the noble metal is transferred to an oxidation furnace,
Oxygen gas was blown in to oxidize and separated into a copper oxide slag and a molten layer of metallic copper in which precious metals were concentrated. The metallic copper containing noble metal was 10 parts by weight with respect to the transferred amount. This metallic copper was dissolved in nitric acid and hydrochloric acid, gold and silver were sequentially recovered by a wet method, and palladium was recovered by extraction. The recoveries were as high as 97.3, 96.8 and 98.2%, respectively.

Example 2 A polyethylene terephthalate resin waste containing 1000 ppm of palladium was melt-molded and pelletized with a diameter of 5 mm. 100 parts by weight of the obtained pellets are put into a batch heating furnace, and 200 to 45 ° C at 200 ° C / hour up to 200 ° C while flowing a small amount of nitrogen under a sealed atmospheric pressure.
After raising the temperature to 0 ° C at 50 ° C / hour, finish the temperature in 10 minutes.
The temperature was raised to 500 ° C. and held for 30 minutes for heat treatment. The shape of the pellet after heat treatment showed some deformation, but the amount of carbide formed was 5.6 parts by weight (carbon content 91%) and the palladium content was 18690 ppm. Depending on this result,
The residual rate of palladium after the carbonization process is 99.1%.

Next, with respect to 100 parts by weight of this carbide, 40 parts by weight of alumina, 70 parts by weight of silica, 100 parts by weight of slaked lime,
30 parts by weight of copper oxide was added, and the mixture was heated to 1450 ° C. in a heating furnace and kept for 6 hours to melt the mixture, and separated into a layer containing metallic copper containing palladium and an oxide.

Further, the molten metal copper layer containing palladium was transferred to an oxidation furnace, and was blown with oxygen gas to be oxidized, whereby a molten layer of copper oxide (slag) and metallic copper in which palladium was concentrated was separated. A molten layer of metallic copper containing palladium was extracted and dissolved in aqua regia, and palladium was recovered by a wet method. The recovery rate was 97% with respect to the palladium contained in the raw material polyethylene terephthalate resin.

(Example 3) Resin 100 used in Example 2
80 parts by weight of silica powder, which is a carbonization accelerator, was added to parts by weight and melt-molded to obtain pellets having a diameter of 5 mm. 100 parts by weight of the obtained pellets were put into a batch-type heating furnace and heated in a nitrogen atmosphere at 350 ° C / hour up to 200 ° C and 200 ° C / hour from 200 to 450 ° C, and then 10 minutes. The temperature was raised to a final temperature of 500 ° C and held for 30 minutes for heating and carbonization.
No collapse was observed in the shape of the pellet after heating and carbonization. The amount of carbide produced was 99 parts by weight (residual carbon content 18.2).
%) And the palladium content was 1005 ppm. Based on this result, the residual palladium ratio after the heating / carbonization process was
It becomes 99.5%. Next, melting, separation, concentration and recovery were carried out in the same manner as in Example 1 except that 70 parts by weight of copper oxide was used. The recovery rate of palladium was 98%.

(Examples 4 to 7) Pellets having a diameter of 5 mm were prepared by adding slaked lime, which was used as a carbonizing agent in various proportions as shown in Table 1, to polyvinyl acetate resin containing 300 ppm of palladium and mixed and melted. Was prepared and heat-treated in a nitrogen atmosphere using a batch-type heating furnace. Table 1 shows the amount of slaked lime added, the heat treatment conditions, the amount of carbide produced after the heat treatment step, the amount of carbon contained, and the residual rate of palladium.

[0041]

[Table 1]

Here, in Example 4, the amount of slaked lime as the carbonization accelerator added was the smallest, and a slight amount of foaming was observed in the heat treatment step, and scattering of the carbide was observed, but it was within a sufficiently allowable range. In Example 5, the amount of slaked lime added was the largest, and the residual rate of palladium after the heating / carbonization treatment was slightly decreased,
It was within the allowable range in consideration of operational efficiency. Examples 6 and 7 are preferable conditions in which the residual rate of palladium is the highest.

(Example 8) 30 parts by weight of sulfuric acid was added to 100 parts by weight of an ion exchange resin containing 10% of gold used for treatment of a plating waste liquid and mixed to obtain a substantially solid product. Put the obtained solid matter in a rotary kiln and adjust the oxygen concentration.
400 ° C up to 200 ° C in combustion exhaust gas of 0.1% or less
/ Hour, from 200 to 450 ° C., the temperature was raised at 100 ° C./hour, and the final carbonization temperature was raised to 600 ° C. in 1 hour and held for 10 minutes for heating and carbonization. The amount of carbide produced was 53.4 parts by weight, and the gold content was 18.8%. Based on this result, the residual gold rate after the heating and carbonization process is 99.3%. The carbon content was 38.1%.

Next, to 100 parts by weight of this carbide, 200 parts by weight of alumina, 220 parts by weight of calcium carbonate, 80 parts of iron oxide
Parts by weight were added, and the mixture was heated to 1500 ° C. in a heating furnace and held for 4 hours to obtain a molten layer of metallic iron containing gold. The molten layer of metallic iron containing gold was introduced into an oxidation furnace, and oxygen gas was blown therein to oxidize it to separate it into iron oxide (slag) and a molten layer of metallic iron enriched with gold.

The gold-containing metallic iron was dissolved in hydrochloric acid to separate and purify gold. The recovery rate of the obtained gold with respect to the gold contained in the raw material ion-exchange resin was 97.6%.

(Example 9) After being used for the partial hydrogenation of polyisoprene, the concentration converted to metallic platinum was 300 ppm,
Platinum complex (tetrakistriphenylphosphine complex)
20 parts by weight of slaked lime was mixed with 100 parts by weight of the toluene waste liquid of 1. to obtain a sticky almost solid dispersion liquid.
This dispersion is put into a batch-type pyrolysis furnace, and in a nitrogen atmosphere up to 200 ° C, 50 ° C / hour, 200 to 450 ° C.
The temperature was raised at 50 ° C / hour and the temperature was kept at 450 ° C for 30 minutes for heat treatment. The amount of carbide obtained was 26.1 wt.
%), And the platinum content was 1140 ppm. As a result, the residual platinum rate after the heat treatment process is 99.2%.

Next, to 100 parts by weight of this carbide, 30 parts by weight of alumina, 130 parts by weight of silica, 20 parts by weight of slaked lime,
1000 parts by weight of copper oxide was added, and the mixture was heated to 1500 ° C. in a heating furnace and held for 4 hours to obtain a molten layer of metallic copper containing platinum. When the molten layer of metallic copper containing platinum was transferred to an oxidation furnace and was blown with oxygen gas to oxidize it, the molten layer of copper oxide (slag) and metallic copper enriched with platinum was separated.

Metallic copper containing concentrated platinum was dissolved in aqua regia, and gold was recovered by a wet method. The recovery rate was 98.1% with respect to the platinum contained in the platinum complex.

(Comparative Example 1) The same heating and heating conditions as in Example 1 were used except that the temperature condition of the rotary kiln was set to 650 ° C / hour up to 200 ° C and 100 ° C / hour from 200 ° C to 450 ° C. Although carbonization was performed, the organic polymer material contained in the crushed material of the mobile phone caused foaming due to rapid thermal decomposition and fusion between the materials, which made it impossible to operate the kiln.

(Comparative Example 2) The same heating and heating conditions as in Example 1 were used except that the temperature condition of the rotary kiln was set to 600 ° C / hour up to 200 ° C and 250 ° C / hour from 200 ° C to 450 ° C. Although carbonization was performed, the same phenomenon as in Comparative Example 1 occurred and the operation was impossible.

(Comparative Example 3) A small amount of air was introduced into the rotary kiln furnace to carry out heating and carbonization treatment under the same temperature raising conditions as in Example 1 while keeping the oxygen concentration at an average of 5%. The yield of carbide was 15.8%, copper oxide was mainly obtained, and the carbon content was 0.35%. The residual rate of precious metal is
Gold accounted for 78.3%, silver for 71.9%, and palladium for 65.8%. Melting heating, separation and concentration operations were carried out in the same manner as in Example 1 except that 2 parts by weight of coke powder was subsequently added to the carbide to recover the precious metal. The recovery rate was 78.3% for gold and 68.2% for silver. %, And the recovery rate of palladium was 61.9%, showing a significant loss of precious metal recovery.

(Comparative Example 4) The heating rate of the heating / carbonization treatment of Example 2 was changed to 650 ° C / hour up to 200 ° C and 180 ° C / hour from 200 ° C to 450 ° C. The same heat treatment as in Example 2 was performed, but the state after carbonization was violently foamed and scattered, and the residue that could be collected was 1.3 parts by weight and the carbon content was 0.27.
%, The residual palladium rate was 73.1%.

(Comparative Example 5) 100 parts by weight of an ion exchange resin containing 10% of gold used in the treatment of the plating waste liquid was placed in a batch-type decomposition furnace, and the amount of air introduced into the furnace was adjusted to 200 ° C. Heating rate of 500 ℃ / hour, from 200 ℃ to 4
The heating rate up to 50 ° C was 300 ° C / hour, and after that, the temperature was raised to 700 ° C in 30 minutes and burned. The residue left after combustion was 10.5 parts by weight. The carbon content is 0.43%
Met.

This residue was dissolved in aqua regia and gold was recovered by a wet method. The recovery rate was 88.4% based on the gold contained in the raw material ion-exchange resin. It is speculated that a considerable amount of gold was scattered and lost during combustion.

(Comparative Example 6) A toluene waste liquid containing the same platinum medium as the sample used in Example 9 was heated at 950 in a spray incinerator.
Burned at ℃. The ash content in the furnace left after combustion was 1.5 parts by weight, and the carbon content was 0.21%.

This ash was dissolved in aqua regia and platinum was recovered by a wet method. The recovery rate was 53.8% based on platinum contained in the raw material platinum complex.

[0057]

INDUSTRIAL APPLICABILITY The present invention recovers precious metals in the elemental state from wastes such as electronic parts containing trace amounts of precious metals, organic substances and resins containing trace amounts of precious metal catalysts used in the chemical industry. Is the way. Although noble metals have been conventionally collected, it is difficult to achieve a high recovery rate because the content thereof is minute and the carrier has a wide range of forms. According to the recovery method of the present invention, a high recovery rate can be achieved and harmony with the environment can be achieved by a heating / carbonization treatment for preventing a trace amount of precious metal from being oxidized and scattered, and by concentrating the precious metal in the melting step. it can.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hironori Ogata             Asahi 1-6-3 Muroya, Nishi-ku, Kobe City, Hyogo Prefecture             Pretec Co., Ltd. Techno Center F-term (reference) 4K001 AA01 AA04 AA41 BA22 DA01                       DB02 KA01 KA02 KA06

Claims (6)

[Claims] 1. An organic substance containing a noble metal is heated and carbonized to generate a carbide having a carbon content of 0.5% by weight or more, and the carbide is heated together with a flux composed mainly of silica, alumina and a calcium compound. The method is characterized in that the precious metal is melted and separated into a metal layer in which the precious metal is absorbed and a flux layer, the precious metal-containing metal layer is further oxidized to concentrate the precious metal, and then the precious metal is purified from the concentrated precious metal-containing metal layer. The method of recovering precious metals. 2. In the heating / carbonization process, up to 200 ° C 6
Raise the temperature below 00 ° C / hour and increase it from 200 to 450 ° C.
Carbon content is 5% by weight by carbonization by heating up at ℃ / hour or less
The method for recovering a noble metal according to claim 1, wherein the above carbide is obtained. 3. In the heating / carbonizing step, at least one component selected from the group consisting of sodium, potassium and calcium oxides, hydroxides, carbonates, sulfuric acid, carbon, silica and alumina is added. For organic substances,
The method for recovering a noble metal according to claim 1 or 2, wherein 10 to 500% by weight is added. 4. The organic substance is an organic substance containing a noble metal catalyst and / or a waste thereof, and the obtained carbide is heated and melted by adding a metal oxide together with the flux component. The method for recovering a noble metal according to any one of claims 1 to 3. 5. The method for recovering a noble metal according to claim 4, wherein the metal oxide is copper oxide, and the temperature for heating and melting and phase separation is 1100 ° C. to 1500 ° C. 6. The method of recovering a noble metal according to claim 1, wherein the method of purifying the noble metal from the concentrated noble metal-containing metal layer is a wet method using an inorganic acid.