JP2001239231A - Method of recovering heavy metals from discharged material in waste incineration facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of recovering heavy metals from a discharged material in a waste incineration facility, which is capable of separating and removing the heavy metals from the incineration fly ash flying from a waste incineration furnace and collected in a dust collector, a molten salt generated when melting the incineration residue such as the incineration fly ash or the molten fly ash or the like generated when melting, and has high utilization efficiency of a reducing agent used in such a case. SOLUTION: The molten salt 30 generated when melting the incineration residue such as the incineration fly ash is brought into contact with melted aluminum in an electric furnace structured to enable to keep the molten salt in the melting state to reduce the heavy metal chloride contained in the molten salt and the generated heavy metals 31 are separated and recovered from the molten salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to incinerated fly ash scattered from an incinerator and collected by a dust collector when incinerating waste such as municipal waste and sewage sludge, and incineration residues such as the incinerated fly ash The present invention relates to a method for separating and recovering heavy metals from a waste discharged from a waste incineration facility such as a molten salt generated when a molten salt is melted and fly ash generated when the molten salt is melted.

[0002]

2. Description of the Related Art When waste such as municipal waste and sewage sludge is incinerated in a waste incineration facility, fly ash (incinerated fly ash) scattered from the incinerator is collected by a dust collector. The main component of this incineration fly ash is that water-soluble salts such as NaCl and KCl in the waste are vaporized in the incinerator. In addition to this, Pb, Zn, Cu, Cd , C
Since it contains harmful heavy metals such as r, when it is disposed of, a treatment for detoxifying the heavy metals by a method such as a melt-solidification method, a chemical treatment method, and an acid extraction method is performed according to the law. It is said that heavy metals contained in fly ash are mainly in the form of chloride.

[0003] In addition, fly ash (molten fly ash) is also generated when a melting treatment for detoxifying discharged materials such as incinerated fly ash is performed. Since this molten fly ash contains more heavy metals than incinerated fly ash, even when disposing of molten fly ash,
Detoxification processing is performed by the above method.

[0004] Further, in the case where the effluent such as incineration fly ash is melt-processed, some of the salts and heavy metals contained therein remain in the melting furnace and are discharged together with the slag. At this time, a part of the heavy metal remaining in the melting furnace is transferred into the molten salt (molten salt) and discharged. Therefore, even when the molten salt is disposed of, a detoxification treatment is performed by a method such as a chemical treatment method or an acid extraction method.

[0005] Techniques for detoxifying effluents from waste incineration facilities by methods other than those described above are disclosed, for example, in JP-A-63-163.
Japanese Patent No. 315187 discloses an electrolysis treatment in which a molten salt containing molten salt is directly electrolyzed by an electric melting furnace, or a wet treatment in which a molten salt containing molten salt is washed with water or the like to remove heavy metals. A method for doing so is disclosed.

[0006] Another method is to reduce heavy metal chlorides in a molten salt and separate the heavy metals into a metal form. This molten salt treatment method is disclosed in Japanese Patent Application Laid-Open No. 9-314089.
Patent No. 4,087,086, a reducing agent is added to a molten salt bath generated when melting incineration ash or fly ash discharged from a refuse incinerator in a melting furnace, and heavy metals contained in the molten salt It is characterized in that chlorides are reduced at a predetermined temperature, and heavy metals generated are separated and recovered from molten salts.

[0007]

However, there is a problem with any of the above prior arts. The melt-solidification method of melting incineration residues such as fly ash can simultaneously reduce the volume of incineration residues and stabilize heavy metals, which is a useful method in itself. During treatment, molten salts and fly ash are generated, and a treatment for detoxifying these secondary emissions must be performed. For this reason, the harmless treatment of the incineration residue cannot be completed by the melt-solidification method alone.

[0008] When a chemical treatment method is employed, expensive chemicals such as liquid chelates must be used.

In addition, in the case of using an acid extraction method or a method similar thereto, for example, a method disclosed in Japanese Patent Application Laid-Open No. 63-315187, a complicated apparatus is required to perform the electrolysis treatment. In the case of wet treatment, the waste liquid after washing must be rendered harmless, and equipment and treatment for that purpose are required.

Compared with the above method, Japanese Patent Application Laid-Open No. 9-31408
The method disclosed in Japanese Patent No. 9 can use waste can aluminum as a reducing agent for removing heavy metals,
This seems to be a good way to evaluate,
When this method is adopted, there is a problem that the utilization efficiency of the reducing agent is very low, and a large amount of the reducing agent must be supplied.

According to the description of the embodiment of Japanese Patent Application Laid-Open No. 9-314089, the result of obtaining the utilization efficiency of a reducing agent when 0.5 kg / d of an aluminum can is charged as a reducing agent in a 10 kg / d processing furnace is as follows. , As follows.

The supply amount of aluminum in the embodiment of the above publication corresponds to 50 kg per ton of the material to be treated.
Based on the heavy metal content in the molten salt and the chemical reaction formulas (1) to (5) described in Table 1 of the above publication, the amount of aluminum consumed by reacting with the heavy metal was determined. Heavy metal content Al consumption Pb: 10.6 kg-Pb / t x (26.98 / 207.2) x (2/3) = 0.9 kg / t Zn: 35.8 kg-Zn / t x (26.98 / 65.38) x (2/3 ) = 9.8 kg / t Cu: 2.7 kg-Cu / t x (26.98 / 63.55) x (2/3) = 0.4 kg / t Cd: 0.37 kg-Cd / t x (26.98 / 112.41) x (2/3 ) = 0.06 kg / t Cr: 0.19 kg-Cu / t x (26.98 / 52.0) x (2/3) = 0.1 kg / t Total 11.3 kg / t

According to the results, the amount of aluminum consumed in the reaction was 11.3 kg / t, and 23% (11.3 kg) of the can aluminum charged was actually consumed.
As a remedy to find out that it was only (50 × 100), there is a method of introducing a large amount of a reducing agent. However, this method is disadvantageous in terms of heat and also requires the recovery and reuse of the unreacted reducing agent. Quite difficult.

According to the present invention, incineration fly ash scattered from an incinerator and collected by a dust collector when waste such as municipal waste and sewage sludge is incinerated, and incineration residues such as this incineration fly ash are melt-processed. Heavy metals can be separated and removed with simple equipment from the molten salt generated at the time, molten fly ash generated at the time of melting, and the use efficiency of the reducing agent used at that time is high,
A method for recovering heavy metals from waste incineration plants is provided.

[0015]

The above object is achieved by the following invention. The present invention according to claim 1 separates and collects heavy metals from waste incineration facilities such as fly ash discharged from a waste incinerator, molten salt generated when a waste incineration residue is melted, and molten fly ash. In a furnace capable of holding a molten salt in a molten state, by contacting the discharge from the waste incineration facility with a reducing agent in a molten state, and removing the heavy metal chloride contained in the discharge from the waste incineration facility. It is characterized in that the product is reduced, and the generated heavy metal is separated and recovered from the molten salt.

According to a second aspect of the present invention, in the first aspect of the present invention, the reducing agent in a molten state is held as a molten bath, and the molten bath is selected from electromagnetic induction stirring, gas publishing, and mechanical stirring. It is characterized in that the waste from the refuse incineration facility is charged and brought into contact with the molten bath while stirring by at least one or more of the stirring operations.

According to a third aspect of the present invention, in the second aspect, a reducing gas is blown into a molten bath of the reducing agent to prevent the reducing agent from deteriorating.

According to a fourth aspect of the present invention, in the third aspect, the reducing fluid blown into the molten bath of the reducing agent is a fluid containing hydrogen or a hydrocarbon compound.

According to a fifth aspect of the present invention, in the first aspect of the present invention, when the waste discharged from the refuse incineration facility is a molten salt, the reducing agent in a molten state is sprayed or dropped and charged into a molten salt bath. It is characterized by contact.

A sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects of the present invention, the reducing agent mainly contains a metal which is more noble than a heavy metal.

According to a seventh aspect of the present invention, in any one of the sixth aspects of the present invention, the reducing agent is Ca, Mg, Al, Na, K,
It is characterized by containing at least one kind of metal as a reducing component from a metal group consisting of Ti and Zr.

[0022] The invention of claim 8 is the invention according to any one of claims 1 to 7, wherein the discharge from the incineration plant is brought into contact with a reducing agent to reduce the heavy metal chloride contained in the discharge. The temperature for reduction is in the range of 700 ° C to 1000 ° C.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects of the present invention, the means for recovering the generated heavy metal is a gravity separation method.

According to a tenth aspect of the present invention, there is provided the first to eighth aspects.
In any one of the inventions, the means for collecting the generated heavy metal is a centrifugal separation method.

The invention of claim 11 is the invention of claims 1 to 8
In any one of the inventions, the means for recovering the generated heavy metal is a filtration separation method.

According to a twelfth aspect of the present invention, there is provided a method for removing heavy metals from waste incineration facilities such as fly ash discharged from a waste incinerator, molten salt generated when a waste incineration residue is melted, and molten fly ash. In the method of separating and recovering, in a furnace capable of holding a molten salt in a molten state, the waste from the waste incineration plant and a molten material containing a metal less heavy than a heavy metal as a reducing agent, contact the waste, Reacting with heavy metal halides contained in the effluent of a waste incineration plant to produce heavy metals and halides of the base metal, separating and recovering the generated heavy metal from the molten salt, and evaporating the base metal And condensing and recovering the halide.

The present invention has been made based on the following studies. As described above, the main components of fly ash discharged from waste incinerators and furnaces that melt the incineration residues are salts such as NaCl and KCl, and heavy metals contained therein are mainly chloride. It exists in the form of things.
The salts (including heavy metal chlorides) in the fly ash do not include those having a melting point higher than 700 to 800 ° C. In addition, the salts in the fly ash are a mixture of various types of salts. The melting point is below 700 ° C. Therefore, fly ash is reduced to 700
If heated above ℃, the salts contained therein will be in a molten state.

In this way, if the salts in the fly ash are brought into a molten state, a treatment for removing heavy metals can be performed in the same manner as the molten salt discharged from the melting furnace of the incineration residue.

For this reason, the present inventors first applied a method for reducing heavy metal chlorides to separate heavy metals in the form of metal to the treatment of both fly ash and molten salt.
Studies have been made to solve the problems of the method described in Japanese Patent No. 14089.

In the examination of the prior art, Japanese Patent Application Laid-Open
When the treatment for removing heavy metals in the molten salt by the method disclosed in Japanese Patent No. 314089, the efficiency of utilization of aluminum added as a reducing agent was low because most of the input aluminum remained unreacted or oxidized. It is highly likely that it has been lost due to reaction with other substances. Therefore, it is difficult to say that JP-A-9-314089 does not sufficiently describe the specific furnace capacity and residence time, that is, the time required for the reaction. As a result, the following findings were obtained.

(1) Immediately after the introduction of aluminum, a solidified layer of a molten salt is formed on the surface thereof, and then the aluminum is heated by heat transfer from the molten salt bath side, so that the aluminum-molten salt contact surface is formed. Since the reduction reaction of the heavy metal chloride proceeds, this reaction takes time. Particularly, when waste aluminum such as aluminum can is used, the reduction reaction is hindered and delayed due to the presence of a coating agent, an oxide film layer, or a residue thereof on the surface thereof.

(2) When heavy metal chloride is reduced on the contact surface of aluminum-molten salt, fine heavy metal particles remain on the aluminum surface, and the aluminum surface is poisoned with heavy metal (as a reducing agent). State of not working)
Therefore, it is inevitable that the use efficiency of the reducing agent becomes low.

Considering the above problems in more detail,
Heating time (waiting time) required for the input aluminum to start the reduction reaction, which was taken up as a problem of the above prior art, and that the progress of the reaction is hindered by a coating film or an oxide film on the aluminum surface. The fact that poisoning of the aluminum surface inhibits the progress of the reaction is a particular problem that occurs when solid aluminum is used as a reducing agent.

Based on the results of this study, in the present invention, in order to prevent the above-mentioned problem from occurring,
A process of bringing aluminum as a reducing agent into a molten state and bringing the molten aluminum into contact with a molten salt is performed. If the molten aluminum is brought into contact with the molten salt, the reduction reaction of the heavy metal chloride is immediately started, so that the processing time is reduced.

Further, if the reaction is carried out while stirring the inside of the container containing the molten aluminum and the molten salt,
The mixing and dispersion of the two are improved, and the reduction reaction of the heavy metal chloride is further promoted.

When the reducing agent is solid aluminum,
Since the heavy metal produced by the reduction reaction is in the form of fine particles attached to the surface of the solid aluminum, it is very difficult to separate and collect the heavy metal. In the present invention, since aluminum is in a molten state, fine particles of heavy metal generated at the interface with the molten salt move with the flow of molten aluminum by an operation such as stirring, and are collected by being gathered at the furnace bottom. And easy separation of heavy metals.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION In a molten salt, a heavy metal contains PbCl.
₂ , contained in the form of chlorides such as ZnCl ₂ , CuCl, CdCl ₂ and CrCl ₃ . When aluminum is added as a reducing agent to these heavy metal chlorides, 700 ° C.
At a temperature within the range of 1000 ° C., the following formulas (1) to (5)
The reaction of the formula proceeds easily, quickly and efficiently, and the heavy metal chloride is reduced to produce a heavy metal and a heavy metal chloride. 3PbCl ₂ + 2Al = 3Pb + 2AlCl ₃ (1) 3ZnCl ₂ + 2Al = 3Zn + 2AlCl ₃ (2) 3CuCl + Al = 3Cu + AlCl ₃ (3) 3CdCl ₂ + 2Al = 3Cd + 2AlCl ₃ (4) CrCl ₃ + Al = Cr + AlCl ₃ ... (5)

The heavy metal produced as described above is Na
Since it does not dissolve in the molten salt composed of Cl, KCl and CaCl ₂ , it is released from the molten salt. Therefore, only heavy metals can be easily separated and recovered from the molten salt.

As the reducing agent, in addition to Al, C
Metals lower than heavy metals such as a, Mg, Al and K can be used.

The reaction between the reducing agent and the heavy metal chloride is 70
It is necessary to perform at a temperature in the range of 0 ° C to 1000 ° C. Below 700 ° C, there are chlorides that do not melt,
If the temperature exceeds 1000 ° C., chloride vaporization becomes intense.
In either case, a normal reduction reaction is not performed.

The produced heavy metal can be easily separated and recovered by a gravity separation method in which the heavy metal is settled and separated by gravity in a vessel, a centrifugal separation method in which the heavy metal is separated by a centrifugal separator, a filtration separation method in which filtration is performed by a filtration membrane, or the like. And the recovered heavy metal can be effectively reused.

Further, heavy metal chlorides such as aluminum chloride generated by the above reaction and vaporized during the treatment at a high temperature can be recovered by condensation.

FIG. 1 is a schematic longitudinal sectional view showing an example of the apparatus used in the present invention. Reference numeral 10 denotes an electric furnace for accommodating a molten salt and performing a reaction for reducing heavy metal chlorides contained therein. Reference numeral 20 denotes an aluminum melting tank. In the figure, 30 is a molten salt, 31 is a heavy metal in a molten state, 32 is molten aluminum, and 33 is scum.

The electric furnace 10 has a structure in which the inner wall is made of carbonaceous brick, the lid 11 is removed, and the molten salt 30 is charged. An external heating device having a heater, an induction coil, and the like is provided on a side portion of the electric furnace 10 so that the charge can be maintained at a high temperature in a molten state. The top of the electric furnace 10 is provided with a supply port 12 for molten aluminum from which a small flow of molten aluminum is sprayed in such a manner as to pierce the molten salt, or has a certain head. Dropped molten aluminum is dropped from the position and flows into the molten salt.

The furnace bottom is provided with a heavy metal discharge port 14 for discharging the heavy metal in a molten state generated by the reduction reaction. A gas such as aluminum chloride vaporized while the melt is kept at a high temperature in the furnace is discharged from the gas outlet 13 and introduced into the condenser 21 to be collected. The condenser 21 may be a cooling plate type or a type using a compound stable at high temperature such as carbon tetrachloride.

In this apparatus, an inert gas such as argon gas is blown from the bottom of the electric furnace to activate the contact between the heavy metal chloride and the reducing agent so that the two can be actively reacted. You may.

When treating a molten salt containing heavy metals using the apparatus having the above-described configuration, the molten salt is charged and maintained at a predetermined temperature, and molten aluminum from which scum has been removed is introduced into the molten salt. Thereby, the molten salt is brought into contact with the molten aluminum. The flowing molten aluminum is dispersed as small droplets and settles in the molten salt,
Since this aluminum is already in a high temperature state, it reacts with the heavy metal chloride at the same time as coming into contact with the molten salt. For this reason, the heavy metal removal processing is completed in a short time. Then, the heavy metal generated by the reaction between the heavy metal chloride and aluminum is deposited on the furnace bottom in a molten state like aluminum.

After the completion of the above reduction reaction, the lid was removed and the electric furnace 1 was removed.
Tilt 0 to discharge only the molten salt from which heavy metals have been removed. Next, the process of charging the molten salt again and performing the above operation to remove heavy metals is repeatedly performed. In this manner, when a certain amount of heavy metal is deposited on the furnace bottom, the heavy metal is discharged from the heavy metal outlet 14 to the outside of the furnace and collected.

FIG. 2 is a schematic longitudinal sectional view showing another example of the apparatus used in the present invention. In FIG. 2, the same parts as those in FIG. This apparatus differs from the apparatus shown in FIG. 1 in that molten salt or fly ash can be charged and brought into contact with molten aluminum contained in a furnace.

In this apparatus, the electric furnace 10 is provided with a wave induction coil 16. Therefore, the molten metal rises due to induction stirring, and the molten salt 30 and the molten aluminum 32 rise.
The renewal of the interface of and the effect of promoting mass transfer promotes the reduction of heavy metal chlorides by molten aluminum,
Heavy metal removal time is greatly reduced. Further, due to the flow of the molten aluminum bath by the induction stirring, the fine particles of heavy metal generated at the interface between the molten salt and the molten aluminum move from the central part of the furnace to the furnace wall side, and are then collected at the furnace bottom. For this reason, since a molten lump of heavy metal is formed at the bottom of the furnace, separation of molten salt and molten aluminum, and separation of molten aluminum and heavy metal can be performed very easily and efficiently.

In the apparatus shown in FIG. 2, an induction coil 16 is provided as a means for stirring the melt in the furnace. However, in the present invention, the means for stirring the melt is limited to electromagnetic induction stirring. Instead, publishing by blowing an inert gas or a reducing gas or the like, mechanical stirring by a stirring blade or the like may be used.

When treating molten salts containing heavy metals using the apparatus having the configuration shown in FIG. 2, an aluminum source such as aluminum can is charged into the electric furnace 10 and heated by an induction coil or a preheating melting burner to melt the molten salt. Let it. Next, if impurities such as scum float on the surface, after removing them, a molten salt or fly ash is charged thereon. When fly ash is charged, the fly ash quickly melts to a molten salt by the action of induction stirring. The contact between the molten aluminum and the molten salt is efficiently performed by the action of the induction stirring, and the reaction between the heavy metal chloride and the aluminum proceeds rapidly.

FIG. 3 is a schematic longitudinal sectional view showing still another example of the device used in the present invention. In FIG. 3, FIG.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. In this apparatus, a gas blowing nozzle 17 is provided at the bottom of the furnace. A gas containing hydrogen gas or a hydrocarbon compound is blown from the gas blowing nozzle 17. When a reducing gas such as hydrogen is blown,
The deterioration of the molten aluminum is prevented, the activity as a reducing agent is maintained, and the basic unit of aluminum is reduced.

[0054]

EXAMPLE 1 Using a test apparatus having the same configuration as that of FIG. 1, a treatment for removing heavy metals from a molten salt generated when a waste incineration residue was melt-processed was performed. 100k test equipment
A molten salt having a processing capacity of g / day was used, and the molten salt processed contained heavy metals in the amounts shown in Table 1.

[0055]

[Table 1]

The above molten salt was charged into an electric furnace of a test apparatus and heated to 850 ° C. Further, can aluminum was charged into an aluminum melting tank and melted. Then, the molten aluminum was dropped on the molten salt to reduce heavy metal chloride in the molten salt. Table 2 shows the heavy metal concentration of the molten salt collected after the generated heavy metal was precipitated after the reduction treatment.
Note that the heavy metal concentration in the molten salt described in this table is a value that sufficiently conforms to the landfill standard value.

[0057]

[Table 2]

[0058]

Example 2 Using a test apparatus having the same configuration as that shown in FIG. 2, a treatment for removing heavy metals from a molten salt generated when a waste incineration residue was melted was performed. 100k test equipment
A material having a processing capacity of g / day was used, and the processing temperature was 850 ° C. The treated molten salt contained the amount of heavy metal shown in Table 1.

In advance, can aluminum is charged into an electric furnace,
Melting was performed by induction heating to prepare a molten aluminum bath in the furnace. Then, after removing the scum generated on the surface, a molten salt was charged on the molten aluminum bath and brought into contact with the molten aluminum. The weight ratio of molten salt to aluminum in the furnace was set to be about 200 kg to 2 tons of aluminum per ton of molten salt.

Although the amount of aluminum consumed is 1/5 or less of the aluminum charge, the operation status and reaction efficiency could be maintained until the end of treatment by holding a large amount of molten aluminum in the furnace. The aluminum equivalent consumed at the appropriate timing was charged as solid aluminum to maintain this amount balance.

Further, induction stirring was continued to accelerate the reaction for reducing heavy metal chlorides in the molten salt. And
The process was continued until the concentration of heavy metals in the molten salt was about the same as in Example 1. The processing time at this time was reduced to about 1/3 of that of the first embodiment. It is considered that the reduction in the required treatment time is due to the appearance of the effect of stirring the molten aluminum bath. Table 2 shows the heavy metal concentration of the molten salt collected after the generated heavy metal was precipitated after the reduction treatment.

[0062]

Embodiment 3 Using a test apparatus having the same configuration as that shown in FIG. 3, a treatment for removing heavy metals from a molten salt generated when a waste incineration residue is melt-processed was performed. 100k test equipment
A material having a processing capacity of g / day was used, and the processing temperature was 850 ° C. The treated molten salt contained the amount of heavy metal shown in Table 1. The weight ratio of molten salt to aluminum in the furnace was set to be about 38 kg of about 1 ton of aluminum per 1 ton of molten salt.

In this test, the molten aluminum bath was stirred while blowing hydrogen gas from a gas blowing nozzle, and the treatment was continued until the concentration of heavy metals in the molten salt was about the same as in Example 1. The processing time at this time was reduced to about 1/5 of the case of the first embodiment. It is considered that the reduction in the required treatment time was due to the fact that the activity of the molten aluminum was always maintained and the reaction between the heavy metal chloride and the aluminum was promptly performed by blowing the hydrogen gas. Table 2 shows the heavy metal concentration of the molten salt collected after the generated heavy metal was precipitated after the reduction treatment.

[0064]

Comparative Example A molten salt containing heavy metals in the amounts shown in
The temperature is maintained at 50 ° C., in which 500 tons of molten salt
At a rate of kg, can aluminum was charged as it was and a treatment for removing heavy metals was performed. This process was continued until the concentration of heavy metals in the molten salt was about the same as in Example 1. Table 2 shows the concentration of heavy metals in the molten salt after the reduction treatment.

The processing time at this time was 2.5 times that of the first embodiment. In addition, the basic unit of aluminum was 10 times that of Example 1.

As is clear from the comparison between the results of the above Examples and Comparative Examples, when the molten salt is treated by the method of the present invention, the supply amount of aluminum as a reducing agent is greatly reduced, and the treatment amount is reduced. Since the time is remarkably shortened, heavy metals can be separated and recovered from the molten salt with extremely high efficiency.

[0067]

As described above, according to the present invention, when waste such as municipal solid waste and sewage sludge is incinerated, the incinerated fly ash scattered from the incinerator and collected by the dust collector is provided. Molten salt generated when melting incineration residues such as incineration fly ash,
Heavy metals, such as Pb, Zn, Cu, Cd, and Cr, can be easily separated and recovered from the waste discharged from the waste incineration facility, such as the fly ash generated during the melting, with simple equipment.

Further, the supply amount of the reducing agent used for removing heavy metals is greatly reduced, and the processing time is significantly shortened. Therefore, heavy metals can be separated and recovered from the molten salt with extremely high efficiency. can do.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing an example of an apparatus used in the present invention.

FIG. 2 is a schematic longitudinal sectional view showing another example of the device used in the present invention.

FIG. 3 is a schematic longitudinal sectional view showing still another example of the device used in the present invention.

[Explanation of symbols]

 Reference Signs List 10 electric furnace 11 lid 12 supply port of molten aluminum 13 gas discharge port 14 heavy metal discharge port 15 inlet of molten salt or fly ash 16 induction coil 17 gas injection nozzle 20 aluminum melting tank 21 condensing device 30 molten salt 31 in molten state Heavy metal 32 Molten aluminum 33 Scum

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22B 7/02 C22B 9/02 7/04 9/05 9/02 B09B 3/00 303L // C22B 9 / 05 ZAB 303Z 304G 304Z (72) Inventor Keisuke Nakahara 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Takuya Shinagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroshi Yamamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4D004 AA16 AA37 AB03 AC04 BA05 CA29 CA37 CB04 CB33 CC01 CC11 CC15 DA06 4K001 BA12 BA14 CA02 DA05 DA06 DA07 DA08 EA03 HA02 HA03 HA06 HA07 HA09 HA11

Claims (12)

[Claims] 1. A method for separating and recovering heavy metals from waste incineration facilities, such as fly ash discharged from a waste incinerator, molten salt, and molten fly ash generated when a waste incineration residue is melt-processed. In, in a furnace in which the molten salt can be maintained in a molten state, the discharge of the waste incineration facility and the reducing agent in a molten state are brought into contact, and the heavy metal chloride contained in the discharge of the waste incineration facility is removed. A method for recovering heavy metals from effluent from a waste incineration plant, comprising separating and recovering heavy metals generated by reduction from molten salt. 2. A molten reducing agent is held as a molten bath, and the molten bath is subjected to at least one stirring operation selected from electromagnetic induction stirring, gas publishing, and mechanical stirring.
The effluent of a refuse incineration plant is charged and brought into contact with the molten bath while stirring by more than one kind of stirring operation.
the method of. 3. The method according to claim 2, wherein a reducing gas is blown into the molten bath of the reducing agent to prevent the reducing agent from deteriorating. 4. The method according to claim 3, wherein the reducing fluid blown into the molten bath of the reducing agent is a fluid containing hydrogen or a hydrocarbon compound. 5. The method according to claim 1, wherein when the effluent from the refuse incineration facility is a molten salt, the reducing agent in a molten state is sprayed or dropped into a molten salt bath and brought into contact therewith. 6. The method according to claim 1, wherein the reducing agent is mainly composed of a metal which is lower than a heavy metal.
A method for treating a molten salt according to claim 5. 7. The method according to claim 7, wherein the reducing agent is Ca, Mg, Al, Na,
7. The method for treating a molten salt according to claim 6, wherein at least one metal selected from the group consisting of K, Ti, and Zr is contained as a reducing component. 8. The temperature at which the effluent of a refuse incineration plant is brought into contact with a reducing agent to reduce heavy metal chlorides contained in the effluent is in the range of 700 ° C. to 1000 ° C. The method of claim 7. 9. The method according to claim 1, wherein the means for collecting the generated heavy metal is a gravity separation method. 10. The method according to claim 1, wherein the means for collecting the generated heavy metal is a centrifugal separation method. 11. The method according to claim 1, wherein the means for recovering the generated heavy metal is a filtration separation method. 12. Heavy metals are separated and recovered from waste incineration facilities, such as fly ash discharged from a waste incinerator, molten salt, and molten fly ash generated when a waste incineration residue is melt-processed. In a method, in a furnace in which a molten salt can be maintained in a molten state, an effluent of the waste incineration plant is brought into contact with a melt containing a metal which is lower than heavy metal as a reducing agent, and the waste incineration plant is discharged. Reacts with the heavy metal halide contained in the product to produce a heavy metal and a halide of the base metal, separates and recovers the generated heavy metal from the molten salt, and condenses the vaporized base metal halide. A method for recovering heavy metals from the effluent of a waste incineration facility, wherein the heavy metal is recovered.