JP2004267987A - Thermal decomposition treatment of waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of simply and inexpensively performing dechlorination treatment or desulfurization treatment at the time of pyrolysis of a waste containing iron, polyvinyl chloride and a rubber such as car shredder dust, a tire or the like and to together provide a method of effectively utilizing resources. <P>SOLUTION: In the method of pyrolytically treating waste by any one of a waste incineration method, a retarded combustion method for waste and a method of indirectly heating waste from the outside, a calcareous substance containing at least one of quicklime, slaked lime and calcium carbonate is supplied along with waste to pyrolytically treat the waste and the residue after pyrolysis is used as an auxiliary raw material for iron making process. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for thermally decomposing waste.
More specifically, for example, the present invention relates to a method for thermally decomposing waste containing iron, PVC, and rubber, such as automobile shredder dust and tires.
[0002]
[Prior art]
Automobile shredder dust is generated during the recycling process of scrapped vehicles and accounts for 20 to 30% of the weight of the vehicle, impeding resource recycling.
The constituent materials of this shredder dust are various such as metals such as iron, copper, zinc, and aluminum, plastics, rubbers, glasses, and fibers, and contain various elements. Similarly, city garbage and the like also contain various elements.
All of them inevitably contain environmentally harmful substances such as chlorine and sulfur due to vinyl chloride, and the treatment of these wastes is a major environmental problem.
[0003]
Therefore, various methods have been conventionally proposed as a method for treating waste containing a large amount of chlorine compounds.
For example, JP-A-7-55121 and JP-A-8-278015 disclose methods for removing chlorine from waste. The framework consists of a dechlorination process for removing chlorine from waste and a combustible combustion process for completely burning the dechlorinated waste.
However, this method has a problem that the processing is performed in two stages and the equipment cost is enormous.
[0004]
On the other hand, Japanese Patent Application Laid-Open No. Hei 7-119939 discloses a method for removing chlorine and sulfur caused by waste. The publication discloses a method for thermally decomposing, burning, or gasifying waste containing plastic, in which a Ca compound is added to waste containing plastic, and chlorine in the waste is reacted with Ca for treatment. A treatment method in which a Ca compound is added by spraying an aqueous solution onto waste containing plastic is described.
However, in this method, it is necessary to prepare a calcium compound in the form of an aqueous solution and to provide a spraying mechanism, so that there is a problem that the capital investment load is large and the operation method is complicated.
In general, a method is known in which fine powder of a calcium compound is added to flue gas to react with chlorine or sulfur, and then the fine powder is recovered. However, a dust collector is required, and equipment and operation costs are required. However, there was a problem that it became expensive.
[0005]
Further, JP-A-6-145735 discloses that a slag and, if necessary, a basicity adjuster composed of limestone, silicate-based crushed stone and the like are introduced into a waste melting furnace to reduce NOx and SOx in exhaust gas, and A method is disclosed in which a slag having a stable composition is recycled.
However, this method is a method of improving the quality of the molten slag, and is different from the method of using the residue obtained by thermally decomposing the waste without melting it as an auxiliary material in the iron-making process as in the present invention. Are completely different.
[0006]
[Patent Document 1] JP-A-7-55121 [Patent Document 2] JP-A 8-278015 [Patent Document 3] JP-A 7-119939 [Patent Document 4] JP-A 6-145735 ]
[Problems to be solved by the invention]
As described above, in the conventional method, the equipment cost and the treatment cost when dechlorinating or desulfurizing the waste by thermal decomposition treatment or the like are increased, and further, the added value of the product after treatment is improved. Was not solved.
Therefore, the present invention provides a method for easily and inexpensively performing a process of dechlorination and desulfurization at the time of pyrolysis of waste including iron, PVC, and rubber such as automobile shredder dust and tires, and It is an object of the present invention to provide a method that can effectively use the information.
[0008]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems of the prior art, and simultaneously removes chlorine and / or sulfur during pyrolysis of waste containing iron, PVC, and rubber such as automobile shredder dust and tires, and simultaneously removes by-products. A method that can easily and inexpensively perform the processing of dechlorination and desulfurization by inexpensively treating the residue as a desulfurizing agent used in the iron making process, and at the same time, provide a method that can effectively use resources The gist is as follows, as described in the claims.
[0009]
(1) In a waste pyrolysis treatment method in which waste is pyrolyzed by any of incineration, suppression combustion, and indirect heating from the outside,
Along with the waste, quicklime, slaked lime, lime-based substances containing one or more of calcium carbonate are supplied and pyrolyzed,
A method for thermally decomposing waste, wherein the residue after the pyrolysis is used as an auxiliary material in an iron making process.
(2) The thermal decomposition treatment method for waste according to (1), wherein the treatment temperature of the thermal decomposition is 500 to 760 ° C.
(3) The method for thermally decomposing waste according to (1) or (2), wherein the lime-based material is in a powder form having an average particle diameter of 1 mm or less.
(4) The thermal decomposition treatment method for waste according to any one of (1) to (3), wherein the residue after the thermal decomposition is used as an auxiliary material for hot metal desulfurization.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described in detail with reference to FIG.
FIG. 1 is a diagram showing a process flow illustrating an example of an embodiment of a waste thermal decomposition treatment method according to the present invention.
First, lime-based substances containing one or more of quick lime, slaked lime, and calcium carbonate are supplied together with wastes including iron, vinyl chloride, and rubber such as shredder dust and tires generated from end-of-life vehicles and pyrolyzed. (S-1).
By this pyrolysis, waste can be carbonized, and volatile components can be evaporated to produce gas and oil.
[0011]
At this time, CaO, a lime-based substance supplied together with the waste, reacts with chlorine and sulfur to be fixed, so that chlorine and sulfur do not transfer to the generated gases and oils. Kind can be created.
In particular, chlorine is an element that generates dioxin. Conventionally, in order to detoxify dioxin in generated gases and oils, chlorine is heated and decomposed at a high temperature of about 1200 ° C., and then quenched. Although a method of preventing resynthesis has been performed, according to the present invention, such a treatment is not required since chlorine itself does not transfer to gas or oils.
The thermal decomposition method in the present invention may be any method as long as the waste can be steamed and carbonized, and may be any one of incineration, suppressed combustion, and indirect heating from the outside.
Here, incineration refers to directly burning the waste itself, suppression combustion refers to partial combustion as insufficient air combustion to generate reducing gas, and indirect heating from the outside refers to, for example, external heating. Indirect heating using a thermal rotary kiln or the like to generate high calorie gas.
[0012]
The thermal decomposition treatment temperature is preferably from 500 to 760 ° C.
If the temperature is lower than 500 ° C., the volatile components in the waste do not evaporate sufficiently, so that the generation ratio of gas and oils is low. In addition, if the temperature exceeds 760 ° C., for example, the service temperature of heating equipment such as an externally heated rotary kiln made of steel is reduced. Because it will exceed.
Next, metals are separated by sieving or the like (S-2).
The separated metals such as iron can be recycled as raw materials for ironmaking.
The residue left by the sieving is used as an auxiliary material in an iron making process, such as a desulfurizing agent for hot metal, and can produce slag used in steel products, roadbed materials, cement, and the like (S-3). .
The lime-based material supplied together with the waste containing one or more of quick lime, slaked lime, and calcium carbonate fixes the sulfur content as described above. , The desulfurization treatment can be performed easily and inexpensively.
[0013]
Further, it is preferable that the lime-based material is in the form of powder having an average particle diameter of 1 mm or less.
Since the average particle size of a typical hot metal desulfurizing agent conventionally used is 1 mm or less, it can be easily replaced with a conventional desulfurizing agent by setting it to a size equivalent to this.
When the lime-based substance supplied together with the waste is insufficient, it is preferable to add the lime-based substance appropriately at the time of desulfurization.
Further, chlorine contained in the residue has a function of increasing the fluidity of slag generated in the iron making process, and can improve production efficiency.
In this way, waste containing iron, PVC, and rubber, such as automobile shredder dust and tires, is thermally decomposed into clean gases and oils, and the remaining residue can be used as an auxiliary material in the iron making process. Therefore, it is possible to provide a method capable of easily and inexpensively performing the processing of dechlorination and desulfurization, and also provide a method capable of effectively utilizing resources.
[0014]
【Example】
Using an externally heated rotary kiln having an inner diameter of 900 mm and a length of 6000 mm, a thermal decomposition experiment was conducted at 400 to 800 ° C. for a composite waste of shredder dust and tire containing about 50 mm in outer diameter and containing chlorine and sulfur. The feed rate of the waste is 190 kg / hr.
A lime-based substance (quick lime) having an average particle size of 1 mm or less was supplied to the kiln at 15 kg / hr.
As a result of this experiment, it was found that the dechlorination rate on the gas side became 70% or more in the range of the thermal decomposition treatment temperature of 500 to 760 ° C. This is expressed by the interaction between the rate at which chlorine reacts with calcium and the reaction by which the reaction products decompose. It was also found that about 90% of S in the gas was removed.
Thus, the reason why the chlorine and sulfur content in the gas and oils generated by the thermal decomposition can be removed is considered that CaO of the lime-based substance reacts with chlorine and sulfur and is fixed to the residue side. .
Further, it was confirmed that the residue containing the lime-based substance produced in this example was excellent in the ability to fix and remove the sulfur content in the molten steel by using it as a hot metal desulfurizing agent.
[0015]
【The invention's effect】
According to the present invention, for example, chlorine and / or sulfur are simultaneously removed during pyrolysis of waste containing iron, PVC, and rubber such as automobile shredder dust and tires, and the by-product residue is used in an iron making process. It provides a method that can easily and inexpensively perform the processing of dechlorination and desulfurization by inexpensively treating it as a desulfurizing agent, and at the same time, it can provide a method that can effectively use resources. It works.
[Brief description of the drawings]
FIG. 1 is a diagram showing a process flow showing an example of an embodiment of a method for thermally decomposing waste in the present invention.

Claims (4)

In the waste pyrolysis treatment method in which waste is pyrolyzed by any of incineration, suppression combustion, and indirect heating from the outside,
Along with the waste, quicklime, slaked lime, lime-based substances containing one or more of calcium carbonate are supplied and pyrolyzed,
A method for thermally decomposing waste, wherein the residue after the pyrolysis is used as an auxiliary material in an iron making process. The method of claim 1, wherein the temperature of the thermal decomposition is 500 to 760C. The thermal decomposition treatment method for waste according to claim 1 or 2, wherein the lime-based substance is in a powder form having an average particle diameter of 1 mm or less. The thermal decomposition treatment method for waste according to any one of claims 1 to 3, wherein the residue after the thermal decomposition is used as an auxiliary material for hot metal desulfurization.

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