JP3304734B2 - How to treat shredder dust - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detoxifying shredder dust generated by crushing discarded automobiles and home electric appliances, reducing the volume and recycling the shredder dust. More specifically, when shredder dust is converted to fuel, it is dechlorinated, its metal can be recovered using an existing smelting furnace, and the carbide, oil, and gas recovered by the conversion to fuel are manufactured. The present invention relates to a recycling method for reusing an energy source such as a smelting furnace for full utilization.

[0002]

2. Description of the Related Art At present, most of shredder dust is landfilled, but the amount of generated dust is rapidly increasing, and more than 1 million tons of dust is generated annually, and the disposal site is tight. Therefore, an effective treatment method that does not rely on landfill is required. Further, in conventional landfill treatment, environmental pollution due to elution of heavy metals and oils causes serious social problems. As a countermeasure, a method of incinerating shredder dust to reduce the volume and at the same time, recovering heat is considered promising.

However, shredder dust is mainly a mixture of plastic waste including chlorine-containing plastics such as polyvinyl chloride, which is a coating material for wiring, and metal scraps. When the waste is put into a furnace and burned, a large amount of incineration ash remains, and heavy metals remain in the incineration ash, so that it cannot be landfilled as it is, and post-treatment such as melting and solidification is required. Moreover, since it contains chlorine, there is a risk that dioxin will be generated during normal heat treatment, and corrosion of equipment due to hydrogen chloride will be a problem. Thus, these problems cannot be solved by simple incineration of shredder dust.

[0004]

SUMMARY OF THE INVENTION The present invention provides a detoxification / recycling method which solves the above-mentioned conventional problems in the disposal of shredder dust, and performs a dechlorination treatment when the shredder dust is thermally decomposed. The existing smelting furnace can be used to recycle the carbide, oil, and gas recovered in the pyrolysis process as an energy source for the smelting furnace, and smelt the metal in dust. An object of the present invention is to provide a processing method for detoxifying and recycling resources by collecting them in a furnace.

[0005]

According to the present invention, (1) shredder dust to which a calcium-containing basic inorganic compound is added is carbonized in a non-oxidizing atmosphere at a temperature of 300 to 600 ° C. to remove chlorine contained in the dust. Is reacted with metal dust and calcium components in dust to generate chlorides that do not volatilize at the carbonization temperature, thereby fixing the chlorine contained in the residue and separating it from the carbonization gas. Is washed to dissolve and remove water-soluble metal chlorides and dechlorinated, and then the washing residue is introduced into a smelting furnace to oxidize iron and calcium contained in the residue to form slag.
A method for treating shredder dust, characterized by melting and recovering the metal component in the residue while reusing the dry distillation gas or the dry distillation oil obtained by condensation thereof as fuel.

Further, according to the present invention, the following specific method is provided for the above-mentioned method for treating shredder dust. (2) The treatment method according to (1), wherein the cleaning residue is introduced into a non-ferrous smelting furnace. (3) The processing method according to the above (2), wherein a smelting furnace of copper smelting or lead smelting is used as the non-ferrous smelting furnace. (4) After the carbonization, carbonized carbon is recovered from the washed residue and the carbonized gas and used as fuel, and the carbonized gas obtained by condensing the carbonized gas is separated into oil and water to recover the carbonized oil, and the carbonized oil and the non-condensed oil (1) to reuse the carbonized gas from the above as fuel
The processing method according to any one of (3). (5) The above washing residue is melted together with a smelting raw material in a non-ferrous smelting furnace, the metal content in the residue is collected in a smelting mat, and the smelting slag is reused as a cement resource.
The processing method according to any one of (1) to (4). (6) slaked lime as a calcium-containing basic inorganic compound;
The treatment method according to the above (1), using quick lime and calcium carbonate. (7) The treatment method according to any one of (1) to (6) above, wherein the dry distillation residue is washed with an alkaline solution, and a metal component leached from the residue is recovered as a hydroxide. (8) The treatment method according to the above (7), wherein after the alkali washing, the pH of the washing wastewater is adjusted to a range of a wastewater regulation value.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The treatment method of the present invention comprises a dechlorination carbonization step of carbonizing shredder dust to perform dechlorination and fuel conversion, and a method of charging a carbonization residue into a smelting furnace to recover metal components. Refining process. FIG. 1 shows an example of a processing step according to the present invention.

(I) Dechlorination Drying Step Vinyl chloride contained in shredder dust is used in large quantities as a covering material for electric wires. Vinyl chloride itself contains theoretically about 56% by weight (hereinafter abbreviated as%) of chlorine, and its combustion and thermal decomposition behavior is significantly different from that of other polyolefin resins and polystyrene resins. (Above about 200 ° C), decomposes while generating hydrogen chloride.

According to the treatment method of the present invention, shredder dust is carbonized at a relatively low temperature of 300 to 600 ° C. in a non-oxidizing atmosphere in order to avoid the generation of hydrogen chloride.
The chlorine contained in the coating material and the like and the metal dust mixed in the dust react with each other to form a non-sublimable metal chloride, whereby the chlorine content is fixed in the residue and separated from the carbonization gas.

When vinyl chloride for an electric wire covering material is dry-distilled at about 300 ° C. without metal scrap, more than 80% of the contained chlorine is vaporized as hydrogen chloride. On the other hand, shredder dust generally contains 10 to 30% of metal dust. When shredder dust is carbonized in a state in which metal dust is mixed, chlorine or hydrogen chloride generated by decomposition of vinyl chloride is reduced to iron contained in the dust. Reacts with metals such as copper, aluminum, zinc, magnesium, calcium, sodium, and lead to form metal chlorides that do not evaporate at the carbonization temperature, and remain as solids in the carbonization residue, so chlorine gas and hydrogen chloride Almost no gas is generated.

Incidentally, a calcium-containing basic inorganic compound may be added instead of or together with the metal scrap. Slaked lime, quicklime or calcium carbonate is used as the calcium-containing basic inorganic compound. In this case, similarly, chlorine generated by decomposition of the plastic reacts with these calcium compounds to form calcium chloride, which is fixed to the residue. Therefore, when the amount of metal in the waste material is small, chlorine can be easily and inexpensively fixed in the residue by adding these calcium compounds.

The range of the carbonization temperature is suitably from 300 ° C. or higher at which chlorine in the resin is decomposed to 600 ° C. or lower at which most of the resin components in the waste material are decomposed. If the temperature is lower than 300 ° C., dehydrochlorination does not proceed, and if it is higher than 600 ° C., a part of the metal chloride is volatilized and moves into the gas, which is not preferable.

[0013] The dry distillation time is sufficient for the resin to be thermally decomposed and the reaction to proceed sufficiently to complete the formation of the metal chloride. The time required to decompose about 200 g of plastic waste material is generally 30 minutes, depending on the amount and temperature of the waste material.
It is about 60 minutes.

Further, dry distillation is performed in a non-oxidizing atmosphere in which an inert gas such as nitrogen is introduced and air is discharged. In this case, the non-oxidizing atmosphere means that the oxygen concentration is 16 vol% or less. Preferably, an inert gas atmosphere having an oxygen concentration of 4 vol% or less is suitable. Dry distillation in air (oxidizing atmosphere) is not preferable because iron and the like mixed therein are oxidized during dry distillation to form volatile chloride having a high oxidation number. For example, when iron is carbonized in the air, it reacts with chlorine contained in organic waste materials to produce iron (III) chloride FeCl ₃ . This iron chloride (II
I) has a boiling point of about 317 ° C. and volatilizes at a temperature significantly lower than the boiling point of iron (II) chloride, FeCl ₂ (about 1023 ° C.).
Vaporizes during carbonization and does not act to fix chlorine in the residue.

The dry distillation may be performed in multiple stages. For example, primary carbonization is performed at a temperature of about 300 to 450 ° C., preferably 300 to 350 ° C., at which most of the chlorine contained is released, and then the residue is removed at a temperature of 450 to 600 at which most of the resin including the coating material is decomposed. A second carbonization is performed at a temperature of ° C.

By the carbonization treatment, almost all of the chlorine contained in the resin is decomposed and reacts with metal scraps, and remains in the carbonization residue as metal chloride. Therefore, the amount of chlorine gas or hydrogen chloride gas volatilized in the carbonization gas is reduced. Is negligible. Most of the resin is thermally decomposed with the elimination of the contained chlorine and volatilized as a dry distillation gas.

The dry distillation gas is led to a condenser, cooled and condensed to recover the dry distillation liquid, and further the uncondensed gas is led to an alkali liquid, and a very small amount of chlorine remaining in the gas is collected and separated by alkali washing. to recover. The carbonization gas is mainly a hydrocarbon gas and can be reused as a fuel gas. Further, the dry distillate is separated into water and oil by centrifugation or the like, and the oil is recovered as fuel. These carbonized oil and carbonized gas can be used as a part of the fuel in the smelting process and the like.

On the other hand, before introducing the carbonized gas into the condenser, it is guided to a dust trap to collect and recover carbides mixed in the gas, and the carbonized materials contained in the carbonized residue can be recovered and reused as fuel. . After the carbonization contained in the carbonization residue, the residue can be pulverized after washing, and separated and recovered by utilizing the difference in specific gravity. In addition, you may separate and collect | recover using the difference of a shape and a particle size.

Most of the metal chlorides in the dry distillation residue are water-soluble, and the residue is washed to dissolve the metal chloride. The washing may be washing with water or alkali washing with caustic soda or lime. By washing with caustic soda, lime, or the like, the washing solution is neutralized, and metal ions leached from the residue precipitate as hydroxides, which can be separated and collected. In this case, the amount of alkali in the cleaning solution is such that the leached metal content falls within a pH range where hydroxide precipitation occurs. The optimum pH range varies depending on the type of metal and the like, and the amount of alkali may be determined according to each metal type and the like.

If the pH value of the washing wastewater is out of the regulation value of the wastewater, the pH of the wastewater is adjusted again after collecting the metal hydroxide to fall within the regulation value of the wastewater. Specifically, according to the current emission standards, the pH of wastewater is 5.8 to
Since the value is regulated to the range of 8.6, when the value deviates from the regulated value, the pH is adjusted again after recovering the metal hydroxide and adjusted to the above range.

In addition, the metal chloride leached by washing with water can be used, for example, by electrodialysis or ion exchange resin,
The washing liquid may be separated and collected by a conventional method such as a method of boiling to crystallize.

(II) Smelting Step After washing the dry distillation residue, the washed residue is put into a smelting furnace for non-ferrous metal smelting such as copper smelting or lead smelting, and is melted together with the smelting raw material to form a metal component in the residue. Is recovered in a smelting mat and iron and calcium are recovered as smelting slag.
If the shredder dust is directly injected into the smelting furnace without going through the above-mentioned carbonization process, the smelting furnace and flue gas and other equipment will be corroded due to the chlorine gas and hydrogen chloride gas generated by the decomposition of plastics as described above. In addition, there is a problem that the working environment is impaired. According to the present treatment method, such a problem does not occur because the carbonized residue after the carbonization step is introduced into the smelting step in advance.

The type of the smelting furnace into which the carbonization residue is charged is not limited, and various smelting furnaces used in a smelting process or a refining process for melting coarse ore or the like, for example, a smelting furnace, a self- A furnace, a reduction furnace, a reverberatory furnace, a converter, a refining furnace, or a melting furnace, a separation furnace, or a copper making furnace in continuous copper smelting can be used, and these are selected according to the properties of the dry distillation residue.

FIG. 2 shows a processing method using a copper smelting process as an example of the smelting process. In the illustrated copper making process, the copper concentrate is melted in a reverberatory furnace 21 and separated into a FeO-CaO-SiO ₂ slag and a copper sulfide mat containing iron sulfide. Blows air into the molten mat to oxidize iron and expel it to slag, turning copper sulfide into blister copper. The slag is returned to the reverberatory furnace 21, and the copper content is recovered again. The blister copper obtained in the converter 22 is sent to the refining furnace 23, where the impurities in the blister copper are oxidized and volatilized or removed as slag and then reduced. Obtain purified copper. This purified copper becomes an anode for electrolytic smelting. Exhaust gas such as sulfurous acid gas generated in the reverberatory furnace 21 and the converter 22 is guided to a boiler 24 and a cotrel 25 to remove smoke ash.

The residue of the dry distillation of the shredder dust is mainly charged into the reverberatory furnace 21 or the converter 22 depending on its properties.
Melted with copper concentrate or mat, iron and calcium contained in the residue are oxidized to slag,
Separated from the mat. The noble metal is melted in the mat together with the copper, contained in the blister copper, sent to the refining furnace, and finally recovered through the electrolytic process. Further, lead oxide and zinc oxide generated as smoke in the reverberatory furnace 21 and the converter 22 are recovered from the exhaust gas by the boiler 24 and the cotrel 25,
Further, the carbonized matter recovered from the carbonization washing residue and the exhaust gas is used as fuel for the smelting furnace together with the carbonization gas and the carbonization oil. Slag generated in the converter is returned to the reverberatory furnace 21 and reused, and also used as a raw material for cement and an aggregate.

[0026]

The present invention will be specifically described below by way of examples. This embodiment is an exemplification and does not limit the scope of the present invention.

Example 1 (1) Dry distillation process Shredder dust having the composition shown in Table 1 was heated to a temperature of 550 ° C. at a processing rate of 2 tons per hour and continuously carbonized by using an internal heating type continuous carbonization furnace. The residue was washed with 5 m ³ of water per hour, dehydrated and dried on the sun. The carbonized gas was led to a condenser, cooled and condensed to collect the carbonized liquid. Further, the uncondensed gas was led to an alkali solution, and a very small amount of chlorine remaining in the gas was collected and separated by alkali washing, followed by recovery. On the other hand, the carbonized liquid was separated into oil and water by centrifugation, and the carbonized oil was recovered. Table 2 shows the washing residue, the amount of the carbonized gas and the recovered carbonized oil after the alkaline cleaning, the chlorine content, and the calorific value thereof. When the residue was washed with water, lime was partially added to neutralize the residue, and the dissolved metal ions were precipitated again.

The total calorie of the dry distillation product of shredder dust is about 1060 kg / h in terms of coal, and the calorie (140 kg in terms of coal) required for dissolving incombustibles (490 kg / h) such as metals contained in the residue. / h) minus about 9 in terms of coal
A heat of 00 kg / h could be recovered. Further, the chlorine content of the dry fraction and the washing residue is as shown in the following table, and it was confirmed that even if the washing residue was put into a smelting furnace, there was no danger of causing chlorine damage.

[0029]

[Table 1]

[0030]

[Table 2]

(2) Smelting process The dry distillation washing residue having the composition shown in Table 3 obtained in the above dry distillation process was used.
5 kg is sent to the copper smelting process, and together with flux (0.04 kg), copper mat (2.0 kg) and slag (1.
7 kg) and placed in a melting furnace and heated at 1350 ° C. for 1 hour. The components of the resulting copper mat and slag were analyzed, and the results are shown in Table 4. Table 4 also shows the components of smoke ash generated from the furnace.

As shown in the results, when a 1/4 amount of the dry distillation residue was added to the copper mat, the amounts of the copper mat and the slag increased correspondingly to the added amount of the residue, and therefore, the amount of the residue in the residue was increased. The metal component and the non-metal component are absorbed and recovered by the copper mat and the slag, respectively, but the component ratio of the copper mat and the slag is not much different from that before adding the residue, and thus is not affected by the addition of the carbonization residue, and It was confirmed that copper smelting could be continued according to the usual process.

[0033]

[Table 3]

[0034]

[Table 4]

Example 2 Into a continuous copper making process for treating 70 tons / hour of copper concentrate, washing residues produced by the dry distillation treatment of Example 1 were fed together with a flux (14 tons / h) at a rate of 0.86 ton / hour. The components of the output mat and output slag were compared with those without the cleaning residue. The results are shown in Table 5. Even though the washing residue was added, the components remained the same as those without the addition, and the continuous copper making process could be stably performed.

[0036]

[Table 5]

Example 3 and Comparative Example 0.5 kg of the dry distillation washing residue (sample A) of the shredder dust obtained in the carbonization step of Example 1 and 0.5 kg of untreated shredder dust (sample B) not subjected to carbonization. 1350, to which flux (0.04 kg), copper mat (2.0 kg) and slag (1.7 kg) were added in the same manner as in Example 1.
Heated at 0 ° C. for 1 hour. At this time, the generated gas was guided to a scrubber, and cooled by spraying cleaning water. This is sample A,
For B, corrosion of the piping portion (made of SUS316) and the washing water injection nozzle portion (made of SUS316) was repeated 15 times.

As a result, in the case of the sample A which had been subjected to the dry distillation treatment, no visible corrosion of the pipe and the nozzle portion was recognized, and the weight loss of the unused nozzle and the nozzle after the test was zero in the nozzle portion. On the other hand, in the case of Comparative Sample B, it was observed that the pipe and the nozzle portion were slightly discolored. The nozzle part is 0.0
A 7% weight loss was observed.

[0039]

As described above, the treatment method of the present invention comprises a dry distillation step and a smelting step. When processing shredder dust containing a large amount of chlorine-containing plastics such as a vinyl chloride resin, the dry distillation treatment is carried out. By doing so, the problem of chlorine damage caused by the thermal decomposition of the plastic can be solved, and the metal can be recovered at low cost in the smelting process. Further, heat recovery can be achieved by utilizing a carbonized gas, a carbonized gas and a carbonized oil generated by the thermal decomposition of plastic as a fuel. In addition, since slag generated in the smelting process can be used as a raw material for cement or the like, the final waste that must be landfilled as in the related art does not occur, and the problem of shredder dust disposal can be completely solved.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a processing method of the present invention.

FIG. 2 is a process diagram showing an example of a smelting process.

[Explanation of symbols]

 21-reflection furnace, 22-converter, 23-refining furnace

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Susumu Okabe 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Within the Mitsubishi Materials Research Institute (72) Inventor Hitoshi Takeuchi 1-325 Koishikawa 1-chome, Bunkyo-ku, Tokyo Earth Business Center, Mitsubishi Materials Corporation (56) References JP-A-4-150150 (JP, A) JP-A-4-80433 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) B09B 3/00 302

Claims (8)

(57) [Claims] A shredder dust to which a calcium-containing basic inorganic compound has been added under a non-oxidizing atmosphere at 300 to
Dry distillation at a temperature of 600 ° C., and reacting chlorine contained in the dust with metal dust and calcium components in the dust to generate chloride which does not volatilize at the carbonization temperature, thereby fixing the chlorine contained in the residue and carbonizing the residue. While separating from the gas and recovering the carbonized gas, the carbonized residue is washed, and the water-soluble metal chloride is dissolved and removed to dechlorinate.Then, the washed residue is introduced into a smelting furnace to remove iron and iron contained in the residue. Acid calcium
Shrinking dust to promote the formation of slag while melting and recovering the metal component in the residue, and further reusing the dry distillation gas or the dry distillation oil obtained by condensing the same as fuel. . 2. The processing method according to claim 1, wherein the cleaning residue is introduced into a non-ferrous smelting furnace. 3. The method according to claim 2, wherein a smelting furnace for copper smelting or lead smelting is used as the non-ferrous smelting furnace. 4. After the carbonization, carbonized carbon is recovered from the washing residue and the carbonized gas and used as fuel, and the carbonized gas obtained by condensing the carbonized gas is separated into oil and water to recover the carbonized oil. The processing method according to any one of claims 1 to 3, wherein uncondensed dry distillation gas is reused as fuel. 5. The cleaning residue is melted together with a smelting raw material in a non-ferrous smelting furnace, metal in the residue is collected in a smelting mat, and the smelting slag is reused as a cement resource. The method according to any one of the above. 6. The method according to claim 1, wherein slaked lime, quicklime and calcium carbonate are used as the calcium-containing basic inorganic compound. 7. The dry distillation residue is washed with an alkaline solution, and the metal leached from the residue is recovered as a hydroxide.
The method according to any one of the above. 8. The treatment method according to claim 7, wherein after the alkali washing, the pH of the washing wastewater is adjusted to a range of a wastewater regulation value.