JPS62221484A - Method for treating shredder dust - Google Patents

Abstract

PURPOSE:To enhance a utilization degree, by enhancing the economical efficiency of fuel by mixing waste plastic with the combustible substance in shredder dust and converting carbide to activated carbon or an ion exchanger. CONSTITUTION:Shredder dust with preparatory drying moisture of 15% or less is allowed to pack a dry distillation tower to perform thermal cracking dry distillation. The gas in the combustible substance generated in this dry distillation treatment process is converted to oil to obtain liquid fuel while the remaining exhaust gas is burnt as secondary fuel to be used in heat exchange and subsequently exhausted to the open air. The low temp. thermal cracking substance is obtained in a carbide form and coarsely ground in water to elute a heavy metal into water and transferred to a separate tank where separated into a non-combustible substance and a combustible substance by magnetic separation or specific gravity classification. A heavy metal ion sealing agent is added to waste water at this time to separate the same as sludge and the combustible substance is not only mixed with waste plastic to form solid fuel but also activated with steam to be converted to activated carbon which is, in turn, further treated with an acid to obtain an ion exchanger.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for treating shredder dust using a pyrolysis method, and particularly relates to a method for treating shredder dust using a pyrolysis method, and particularly for treating combustible material consisting of charred matter separated by crushing low-temperature pyrolysis products in water. This is a new processing method to obtain more pollution-free solid fuel, activated carbon, ion exchanger, etc.

<Background Art> With the development of motorization, the number of discarded automobiles has increased dramatically, and the disposal of this has become a social problem. Currently, scrapped cars are dismantled, reusable parts are removed, and the remaining scrapped cars are processed and metal scraps are collected. We use a shredding machine called a shredder to process scrapped cars.
The resulting waste is called shredder dust.

Shredder dust consists of waste plastics, rubber, and non-metallic materials such as glass, which account for about 25% of its shredded weight, and it is said that almost all of it is disposed of in landfills.

Recently, since shredder dust is mainly waste plastic and rubber, it has the potential to be used as a high-calorie fuel, and some researchers have discovered that combustible materials can be converted into carbide solids, liquids, or gases by pyrolysis. The technology to extract it is being established. However, in the shredder dust, Pb,
It contains harmful heavy metals such as HE, Mn, and Cd, and whether it is disposed of or used as fuel, there is a problem of environmental pollution, and it is not easy to dispose of them.

The present inventor has developed a method for detoxifying electric furnace dust waste by treating it with a chemical agent containing a chelating agent and forming flocs with portland cement and aluminosilicate, thereby making it possible to dispose of it in the ocean or in a landfill. Kosho 59-2167
This is proposed in issue 5. Also.

We have developed a heavy metal sequestering agent containing a new chelating agent similar to this, and have also proposed a detoxifying agent for heavy metals contained in dust, sludge, and sludge in Japanese Patent Application No. 60-2226016 Problems to be Solved by the Invention Although various methods have been proposed and implemented for the treatment of shredder dust as described above, there are many types of shredder dust,
Because it is a multi-purpose property and has a complex and special composition, it is difficult to treat it in the same way as general waste plastic or waste rubber (tires). In addition, as mentioned above, it is most rational to carbonize to reduce weight and power, and then to landfill or convert it into solid fuel, but this still poses the problem of secondary pollution due to heavy metals and the problem of not being economically profitable. It needed to be resolved.

Means for Solving the Problems> The present invention applies the technique of using these heavy metal ion sequestering agents to the treatment of the shredder dust.

This is a processing method that converts combustible materials, which have traditionally been considered difficult to process, into non-polluting solid fuels or useful products such as activated carbon and ion exchangers, which increases the economic efficiency of fuel by mixing waste plastics with combustible materials. The above problems were solved by increasing the utilization of carbide by making it into activated carbon or ion exchanger with high added value. A process of stirring and crushing the waste water, separating it into combustibles and non-combustibles by gravity separation, washing and dehydrating it, adding a heavy metal ion sequestering agent to the wastewater and separating it as sludge, and converting the combustibles into solid fuel, activated carbon or ion exchange. The process consists of the process of manufacturing the body and the processing method.

The outline of the shredder dust processing method of the present invention is as follows.
As shown in the figure, the process can also be carried out continuously using a rotary kiln, in which shredder dust (pre-dried water content of 15% or less) is first charged into a carbonization furnace and pyrolysis carbonization is performed. The gas in the combustibles generated during the carbonization process is turned into oil and turned into liquid fuel, and the remaining exhaust gas is burned as a secondary fuel and released into the atmosphere after heat exchange (of course, it is released after taking appropriate pollution prevention measures). The exhaust heat and the heat from the secondary combustion of exhaust gas can be used to heat the carbonization furnace.

The low-temperature pyrolysis product is in the form of carbide, which is coarsely pulverized in water to elute heavy metal ions into the water, transferred to another tank, and separated into nonflammable and combustible materials by magnetic separation and gravity classification.
Non-combustible materials are separated into metals, soil, stone, and glass. A heavy metal ion sequestering agent is added to the separated water to coagulate and separate the heavy metal ions as flocs, and the water is l! Use ring.

The metals in the noncombustible materials are mainly iron and copper scraps, and the soil, stone, and glass that are collected contain such small amounts of polluting substances that they can be used for landfill.

The feature of the present invention is in the process of treating the carbonized shredder dust, which is the combustible material, and then in the second stage of commercialization of the carbonized composition. This commercialization process can be broadly divided into two routes. In other words, there are two routes: mixing waste plastics to make solid fuel, and activating steam to make activated carbon, which is then treated with acid to make ion exchangers. Commercialization of these products is achieved by effective elution treatment of heavy metal ions into water and pollution-free treatment by adding heavy metal ion sequestering agents.

If the heavy metal ion sequestering agent contains a metal chelating agent, it can be expected to have some effect, but it is preferable to use one containing diethylthiocarbamic acid, and in particular, an alkaline solution of this, such as polyethyleneimine and carbon disulfide. A mixture of sodium diethyldithiocarbamate, sodium thiosulfate, and sodium sulfide in the reactant of sodium hydroxide becomes a heavy metal ion sequestering agent with extremely good properties. In addition, EDTA, NTA, UDA, etc., which are well-known as clear-1-other agents, can also be used in the same way as diethylthiocarbamine.

Effects> According to the treatment method of the present invention, since the carbonized product is crushed in water, it is easy to separate combustibles and non-combustibles, and there is no fear of pulverized coal explosion. Even if heavy metal ions are present in the combustible material, they will be eluted and removed during the underwater crushing of the carbonized product, and will become inactivated sludge by adding a heavy metal sequestering agent to the wastewater. Even with ion exchangers, heavy metal pollution does not occur. In the case of solid fuel, waste plastic acts as a binder, increases calories, and prevents fuel from absorbing moisture.

<Example> The method for treating shredder dust of the present invention will be explained in more detail with the following example.

1) Visual screening results of shredder dust used in low-temperature pyrolysis treatment of shredder dust are as follows:
As shown in the table. The total amount of combustibles is approximately 68.7%, the total amount of non-combustibles is approximately 22.8%, and the moisture and volatile components are approximately 8.5%.

This is pyrolyzed by carbonization in a rotary kiln at a low temperature of 350 to 500°C for about 20 to 30 minutes to produce combustible materials (mainly char).
Approximately 65%, non-combustible materials (mainly metal, glass, clay) approximately 35%
A mixture of , was obtained.

Table 1 Bulk specific gravity is as shown in Table 1, shredder dust is 0.
15, whereas after carbonization pyrolysis it was about 0.5 and about 3
The size has been doubled, and the volume has been reduced to about 1/3, making post-processing easier.

2) Method for crushing shredder dust carbonized carbon composition and removing heavy metal ions After the shredder dust carbonized carbon composition is discharged from the rotary kiln, it is poured into a tank using water at a weight ratio of 1:10. The iron wire, copper wire, etc. contained in the 2500 rpm+s rotary blade and receiving blade are used to cut the iron wire, copper wire, etc., and the heavy metal ions contained in the carbonized dust are washed out. At the same time, the presence of water can prevent concerns about carbonaceous powder coal explosion.

The pulverized composition is sent to another tank and subjected to specific gravity separation using water, and the composition that floats to the surface is combustible and can be used as solid fuel,
Used as a raw material for activated carbon and ion exchangers. On the other hand, the precipitated noncombustible compositions were sorted into iron, copper, earth, glass, etc. using a classifier.

For the washing water, the heavy metal ions that have been eluted are flocculized using a heavy metal ion sequestering agent with the composition shown in Table 2, and the resulting precipitate is completely separated from the wood and sludge using a conical centrifuge. 、Water is recycled.

Table 2 3) Production of solid fuel Processing of combustibles after pyrolysis into solid fuel is as follows. That is, after mixing 15 parts of crushed polyethylene sheet waste material used for agricultural greenhouses with 100 parts of combustible material (carbonized carbonized material) in a mixer,
The mixture was heated and melted at 0° C., and granulated into pellets approximately 7 to 8 mm in diameter using a granulator to obtain a solid fuel.

Table 3: The obtained solid fuel contains 80% carbide, 13.7% volatile content,
The calorific value was 6300 kcal/kg.

Table 3 compares the heavy metal content in the carbonized carbide before and after the underwater crushing treatment, and it was found that the heavy metal ions were almost completely eluted into water.

4) Production of activated carbon To produce activated carbon from combustible char, steam activation was carried out in a 750°C atmosphere using a known method. At this time, as an additive, caustic soda, caustic potash, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, and zinc hydroxide are used as an approximately equal compound of 1 to 5
Add in % range.

Furthermore, calcium chloride, zinc stearate, and manganese dioxide in approximately equal proportions were added in a range of 1 to 5%.

The surface area of the obtained activated carbon was about 1350 rrr/g, and the adsorption capacity is shown in Table 4.

Table 4 5) Production of carbide ion exchanger 10 parts of the above carbonized activated carbon composition was immersed in 100 parts of concentrated sulfuric acid with a concentration of 95% or more for about 2 hours, and then washed with water to obtain an ion exchanger. The treated product was a cation exchanger containing weakly acidic carboxyl groups in addition to strongly acidic sulfonic acid groups, and its ion exchange capacity was 4.5 meq/g.

<Effects> As detailed above, the shredder dust processing method of the present invention allows easy separation of combustibles and non-combustibles by crushing and separating carbonized products in water, and also eliminates the risk of pulverized coal explosion. This is a safe method with no problems at all. Furthermore, since heavy metal ions are eluted and separated in water, it is possible to obtain solid fuel from combustible materials that is non-polluting and can be used to process waste plastics at the same time, and can also be made into activated carbon and ion exchangers with high added value. This makes it an extremely economical way to obtain various useful products from waste.

In addition, heavy metal ions are captured from the separated waste liquid and turned into sludge, and the waste liquid can be recycled and used, providing thorough pollution control measures. 3 is a flowchart of the method.

Figure 1 atmospheric emissions

Claims (1)

[Claims] 1. After low-temperature pyrolysis of shredder dust, it is stirred and crushed in the presence of water, separated into combustibles and non-combustibles by specific gravity separation, washed and dehydrated, and a heavy metal ion sequestering agent is added to the wastewater. In addition, there is a process of separating sludge and turning combustibles into solid fuel,
A method for treating shredder dust, comprising a step of producing activated carbon or an ion exchanger. 2. The method for treating shredder dust according to claim 1, wherein the heavy metal ion sequestering agent is a chelating agent containing diethyldithiocarbamic acid. 3. The method for treating shredder dust according to claim 1, wherein the solid fuel is obtained by adding waste plastic to a combustible material and granulating it by heating. 4. The method for treating shredder dust according to claim 1, wherein the activated carbon is granulated after activating combustible material with steam. 5. The method for treating shredder dust according to claim 1, wherein the ion exchanger is activated carbon that is treated with an inorganic acid.