JP6960227B2 - How to recycle shredder dust - Google Patents

Description

The present invention relates to a recycling method capable of recovering valuable metals or reusing them as fuel by appropriately treating shredder dust (SR) such as automobile shredder dust (ASR). ..

Shredder dust (SR) refers to a mixture of debris that is discarded as industrial waste after crushing waste home appliances and automobiles with an industrial shredder and collecting metals and the like. Its composition varies depending on the technology / facility of the shredder process and the situation of pre-sorting of waste, so it is not always constant, but the main constituent phases are resin, urethane foam, fiber, rubber, etc., and some metal or glass. SRs that need to be disposed of at managed landfills are required to be recycled, and recycling technology is being developed mainly in both the thermal and chemical fields, and the cement industry is also considering using it as a fuel substitute. (See, for example, Patent Document 1). Further, SR contains valuable metals such as iron, non-ferrous metals, and rare metals, and it is preferable that they can be easily recovered in order to reuse them.

Japanese Unexamined Patent Publication No. 2014-205591

However, the resin content (plastic, urethane, rubber, synthetic fiber waste, harness coating, etc.) in SR is soft (high viscoelasticity) and is intricately entangled with metal, so the resin content is crushed and metal separated as it is. It is difficult to recover and it is also difficult to use it as a fuel substitute.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a method for recycling shredder dust, which can recover valuable metals from shredder dust and utilize the residue as fuel. ..

The method for recycling shredder dust of the present invention is:
Step A, in which the shredder dust is heat-treated at a temperature of 250 to 400 ° C. to embrittle it to obtain embrittled shredder dust containing a resin,
Step B to make the embrittled shredder dust less than X mm (X = 2 to 10),
Step C of removing the magnetic deposit from the embrittled shredder dust of less than X mm by the magnetic force sorting means,
It is characterized by including step D of recovering a precious metal as a heavy product from the embrittled shredder dust from which the magnetic deposit has been removed by an air table.

In the shredder dust recycling method of the present invention, the shredder dust is subjected to a heat embrittlement treatment at a temperature of 250 to 400 ° C. to eliminate the entanglement of the resin and the metal contained in the shredder dust and perform the separation treatment. , Precious metals, etc. can be collected efficiently and with high quality. Furthermore, it is possible to utilize something other than metal as fuel.

In the method for recycling shredder dust of the present invention, it is preferable that the embrittled shredder dust is crushed to reduce the total amount to less than X mm in step B. Since the total amount of embrittled shredder dust is less than X mm, the total amount can be treated, and the recovery efficiency of precious metals and the like can be further improved.

In the shredder dust recycling method of the present invention, it is preferable that the embrittled shredder dust from which the magnetic substance has been removed in step C is divided into a plurality of particle groups having different particle size ranges and subjected to the step D. Since the particles are subdivided into a plurality of particle groups having different particle size ranges and subjected to step D, it is possible to further improve the recovery efficiency of precious metals and the like.

In the method for recycling shredder dust of the present invention, it is preferable to mix wood-based powders or crushed materials when the shredder dust in step A is heat-treated. The entanglement of the resin and the metal is easily eliminated by the mixing of the wood-based powder or crushed material, so that the metal recovery rate is improved. Examples of wood-based powders or crushed materials include vegetable fibers such as wood chips, bamboo chips, and coconut shells.

In the method for recycling shredder dust of the present invention, it is preferable to further include step E in which the recovered material other than the heavy products recovered by the air table in step D is recovered as fuel. By providing such a step, the recovered material other than the metal can be reused as fuel, which is preferable.

In the shredder dust recycling method of the present invention, in step B, the embrittled shredder dust of less than X mm and the embrittled shredder dust of X mm or more are separated, and the metal is removed from the embrittled shredder dust of X mm or more, and the residue is left. further including the step F of recovering as fuel. Such steps by providing the, Ru can be reused residue as a fuel.

In this case, in the method of recycling the shredder of the present invention, the removal of the metal from the Xmm more embrittlement shredder dust in the step F is performed by an eddy current sorting, we recover non-ferrous metals. The reason is that removing the metal improves the calorific value, improves the quality of the fuel, and contributes to the recycling of metal resources.

A conceptual diagram showing the structure of an air table. The conceptual diagram which shows the whole flow of embodiment of the shredder dust recycling method of this invention. The conceptual diagram which shows the whole flow of the modification of the embodiment of the shredder dust recycling method of this invention.

Hereinafter, embodiments of the present invention will be described.

The shredder dust recycling method of the present embodiment includes step A in which the shredder dust is heat-treated at a temperature of 250 to 400 ° C. to embrittle it to obtain embrittled shredder dust, and the embrittled shredder dust is less than X mm (X = 2). To 10), step B for removing the embrittlement from the embrittled shredder dust less than X mm by the magnetic force sorting means, and step C for removing the embrittlement shredder dust from the embrittled shredder dust with the magnetic deposit removed as heavy products by the air table. It is characterized by including step D of recovering the noble metal.

Here, the shredder dust in the present invention is, for example, waste that is discharged in the form of a mixture of waste plastics and other wastes, such as automobile shredder dust (ASR), construction waste plastic waste, and the like. Is a typical one. Here, the waste plastics are synthetic polymer wastes, which are synthetic resin moldings, sheets, tapes, strings, sponges and powders, and synthetic resins. It refers to waste of fibers and synthetic rubber. The other wastes include at least metals and / or earth and stones (glass, concrete, roof tiles, bricks, ceramics, inorganic building materials, earth and sand, etc.), and other wastes such as paper and natural fibers. It can contain wastes such as types, woods, roof tiles, leathers, oils and fats, sludges, incinerated ash, carbon, ceramics, liquids, sludges and the like.

Each step will be described in detail below.

[Step A]
In step A, the shredder dust is heat-treated at a temperature of 250 to 400 ° C. to embrittle it to obtain embrittled shredder dust. By performing heat treatment at the above temperature, the mechanical strength of shredder dust can be lowered and embrittled. For example, if the heating temperature is set to 300 ° C, the heating time is 1.5 hours, and similarly 350 ° C. It is preferable to set the relationship between the heating temperature and the heating time to be inversely proportional, such as 1 hour if the setting is set to 1 and 45 minutes if the temperature is set to 400 ° C. Further, since the preferable relationship between the heating temperature and the heating time differs depending on the size of the shredder dust, the type of the constituent resin, and other conditions, it is preferable to set appropriately.

The heating means for performing the heat treatment may be any one that can be set in the temperature range of 250 to 400 ° C., and examples thereof include a fixed furnace, a stoker furnace, a rotary kiln furnace, a fluidized bed furnace, a vertical furnace, and a multistage furnace.

The heat treatment may be performed in the atmosphere, an oxidizing atmosphere, a reducing atmosphere, or an inert atmosphere, but the oxidizing atmosphere is preferable because the mechanical strength of the shredder dust can be reduced in a shorter time.

In the heat treatment of shredder dust, it is preferable to mix wood-based powders or crushed materials because the entanglement between the resin and the metal can be eliminated and the recovery rate of the metal is improved. Examples of the wood-based powder or crushed material include vegetable fibers such as wood chips, bamboo chips, and coconut shells, and among them, wood chips are preferable because they can be easily crushed when they are recovered as light products. The mixing ratio of wood-based powders or crushed materials is preferably 10 to 30% by mass of the whole including shredder dust.

[Step B]
In step B, the embrittled shredder dust is reduced to less than X mm (X = 2 to 10). In step B, the total amount of embrittled shredder dust embrittled in step A may be less than X mm, or those of X mm or more may be removed to limit the amount to less than X mm.

If the total amount or most of the embrittled shredder dust embrittled in step A is less than X mm, a sieving device is used to exclude the embrittled shredder dust to X mm or more. As the sieving device, a vibrating sieving, a rotary screen, or the like can be used, but there is no particular limitation as long as the sieving device has an X mm mesh and can sift between X mm and more and less than X mm.

If the embrittled shredder dust fragile in step A contains a large amount of embrittled shredder dust of X mm or more, the embrittled shredder dust is crushed to less than X mm by using a crushing device. At this time, the embrittled shredder dust may be sieved and only those having an size of X mm or more may be crushed, or the entire amount may be crushed. Further, it is preferable that after crushing, the sieving device is used for sieving and the one having a size of X mm or more is crushed again.

When large lumps, for example, particles of 20 mm are generated in the embrittled shredder dust, it is preferable to crush and crush them in advance.

As the crusher, a hammer crusher, an impact crusher, a jaw crusher, a roll crusher, a cutter mill, a roller mill, a self-contained crusher and the like can be used. It is preferable to use an impact type hammer crusher or impact crusher as a crushing device in consideration of wear resistance and sizing property for the metal mixed in the embrittled shredder dust.

If the total amount of embrittled shredder dust is less than X mm, it should be configured so that the total amount can be crushed to less than X mm at one time, and then the crushed embrittled shredder dust is sieved to X mm or more. It is preferable to crush. Embrittled shredder dust less than X mm is subjected to step C in the subsequent process.

X is set so that the particle size of the crushed embrittled shredder dust is in the range of 0.5 to 10 mm and is 60% by weight or more in order to ensure good separation accuracy in the air table described later. It is preferable, and when the whole amount is set to be crushed at one time, X = 6 to 9 is preferable. This is because if there are too many particles having a particle size of less than 0.5 mm or too many particles having a particle size of 10 mm or more, the separation accuracy may decrease.

The crushing efficiency can be improved by removing as much metal as possible from the total amount of the embrittled shredder dust treated in step B or the embrittled shredder dust of X mm or more that has been screened. Metal sorting can be performed by magnetic force sorting, eddy current sorting, sorter sorting, and the like.

Eddy current sorting is a method of sorting non-ferrous metals such as aluminum from shredder dust by utilizing the difference in repulsive force based on eddy current. For example, the shredder dust conveyed to the tip side of the conveyor belt by the interaction between the induced current generated inside by receiving the electromagnetic induction action of the moving magnetic field of the rotating magnet body provided on the tip side of the conveyor belt and the moving magnetic field. Some are configured to give a thrust in the direction of rotation of the rotating magnet body and cause the non-ferrous metals to pop out from the surface of the conveyor belt in the direction of the combined force of this thrust and the gravity acting on the non-ferrous metals. As the eddy current sorting device, a rotating magnet type, a orthogonal belt conveyor type, and a rotating cylindrical type are preferable.

[Step C]
In step C, the magnetic deposit is removed from the embrittled shredder dust of less than X mm obtained in step B by a magnetic force sorting means.

The magnetic force sorting device, which is a magnetic force sorting means, is a device that sorts from embrittled shredder dust by magnetically adhering a magnetic metal such as iron. The embrittled shredder dust contains metal scraps, and in order to finally recover precious metals such as gold and silver, general-purpose metals such as iron, which is a magnetic deposit, are sorted and removed from the embrittled shredder dust. The magnetic force sorting device is not particularly limited, but a hanging type or a drum type is preferable.

Here, preferably, by performing wind power sorting by the wind power sorting means, it is possible to remove lightweight objects in advance to reduce the load of shape sorting using the air flow described later and improve the precious metal recovery accuracy. The wind power sorting device, which is a wind power sorting means, is a device for blowing air into the embrittled shredder dust having a size of less than X mm and sorting the embrittled shredder dust into a lightweight material and a heavy material by wind power sorting. When embrittled shredder dust is sorted by wind, lightweight materials are mainly separated into soft waste plastics and fibers, and heavy materials are mainly metal wastes, earth and stone wastes, and large-diameter hard waste plastics. Etc. are sorted. The wind power sorting device is a device that sorts the objects to be sorted according to the difference in the terminal velocity, and the model is not particularly limited. Various wind power sorting devices such as those of the formula can be used. In particular, a structure having a structure in which the separation point between the lightweight object and the heavy object can be arbitrarily changed is preferable. Since the composition of embrittled shredder dust fluctuates to some extent, the balance between the fact that the lightweight portion by wind power sorting can be smoothly converted into fuel by crushing and securing as much lightweight material as possible as fuel. It is preferable to operate the wind power sorting device while adjusting the sorting points as appropriate so as to take a good measure. Then, in step C, the lightweight material sorted by the wind power sorting device is removed.

In step C, when the wind power sorting means is performed, the magnetic force sorting means and the wind power sorting means are performed in the order of, for example, the magnetic force sorting means → the wind power sorting means → the magnetic force sorting means, and the magnetic force sorting means → the wind power sorting means. And it is preferable to remove lightweight objects.

For the embrittled shredder dust of less than X mm used in step C or the embrittled shredder dust treated in step C, non-ferrous metals such as aluminum can be recovered by eddy current sorting in order to improve the recovery efficiency of precious metals. preferable.

[Step D]
In step D, the noble metal is recovered as a heavy product from the embrittled shredder dust from which the magnetic substance was removed in step C by an air table.

The air table uses both airflow and vibration, and selects objects based on the difference in resistance to airflow and the ease of rolling due to vibration, that is, the frictional force on the table surface. FIG. 1 shows a structural image of the air table.

The object (Feed) is supplied from the feeder and undergoes a separation operation by the vibrational motion of the table surface (horizontal direction in FIG. 1) and the air flow (vertical direction from bottom to top in FIG. 1). Generally, a heavy object is not easily affected by an air flow, is carried by a vibrating motion, and falls to the left side (Heavy) in FIG. On the other hand, a lightweight object is strongly affected by an air flow and floats to reduce friction with the table surface, slides down the slope of the table, and falls to the right side (Light) in FIG.

Also, the lightest ones are blown up by the air stream and collected by a dust collector (eg, a cyclone). The air table is a parameter that affects not only the air flow but also the vibration and the tilt angle of the table, and by setting these to the optimum values, precious metals can be recovered as heavy products with even higher accuracy. .. The heavy product also contains a high concentration of copper. Further, since lead and chromium, which are repellent components of cement, are also recovered from the heavy products, the amount mixed in the cement as a fuel, which will be described later, is reduced.

When supplying to the air table, the embrittled shredder dust of less than X mm from which the magnetic deposits have been removed in step C is subdivided into a plurality of particle groups having different particle size ranges, and each of these particle groups is supplied to the air table. Is preferable. This makes it possible to improve the recovery accuracy of precious metals and copper.

For example, when the embrittled shredder dust from which the magnetic substance has been removed is less than 8 mm, it is sequentially supplied to a sieving device having sieves having a mesh size of 5 mm and 2 mm, respectively, and a group of particles having a particle size of less than 8 mm and a particle size of 5 mm or more and a particle size of 5 mm. It is divided into a particle group having a particle size of less than 2 mm and a particle group having a particle size of less than 2 mm. Then, a particle group having a particle size of less than 8 mm and 5 mm or more, a particle group having a particle size of less than 5 mm and a particle size of 2 mm or more, and a particle group having a particle size of less than 2 mm are separately supplied to the air table, and the embrittlement shredder is supplied for each particle size range. All you have to do is dispose of the dust. However, the classification diameter in the particle size range can be appropriately adjusted as long as it is X mm or less.

Further, the noble metal concentration can be increased by selecting the heavy products obtained in step D by eddy currents. When a rotating magnet type eddy current sorter is used, the rotation speed of the drum is preferably 4000 rpm or more. This makes it possible to efficiently recover the noble metal of the conductor from the heavy product having small particles.

By the above steps A to D, precious metals such as gold and silver and copper are recovered from the shredder dust. The shredder dust recycling method of the present invention may include the following steps E and F in addition to steps A to D.

[Step E]
In step E, the recovered material other than the heavy products recovered by the air table in step D is recovered as fuel. That is, the dust removed and recovered in steps C and D contributes to reuse as fuel, and the dust is recovered as fuel. When used as a fuel, it is pulverized to 3 mm or less, more preferably 1 mm or less, and further preferably 0.1 mm or less.

[Step F]
In step F, the metal is removed from the embrittled shredder dust of X mm or more sieved in step B, and the residue is recovered as fuel. In step F, since the metal is removed from the embrittled shredder dust of X mm or more, the residue is recovered as fuel through one or more metal sorting means. Examples of the metal sorting means include manual sorting, magnetic force sorting, eddy current sorting, sorter sorting, etc., which are manually sorted by humans. Since it is not necessary to explain the manual sorting and the magnetic force sorting has already been described, the eddy current sorting will be described below. When a rotating magnet type eddy current sorter is used, the rotation speed of the drum may be 4000 rpm or less.

After sorting the eddy currents, it is also possible to recover the metal with a rigid mill for crushing. The vertical mill is a mill refined powder having a predetermined particle size distribution, which is a fine powder, and a particle size distribution on the larger diameter side than the predetermined particle size distribution, by crushing and drying the raw material waste and classifying the fine powder and the coarse powder. It is an apparatus for sorting into milled stones containing coarse powder having a grain size (see Japanese Patent Application Laid-Open No. 2016-89196).

The fuel obtained as described above is preferably used after removing chlorine, that is, desalting. Desalting can be performed by washing with water and desalting, and the chlorine content after desalting is preferably 0.5% by mass or less.

FIG. 2 shows an example of the overall flow of the above embodiment of the shredder dust recycling method of the present invention. As a whole, it is divided into two lines, the H line and the A line. The H line is a line including a step (step B) of reducing the embrittlement shredder obtained in step A to less than X mm. The A line is a line including a step (step D) of collecting and removing embrittled shredder dust less than X mm by magnetic force sorting means and wind sorting means to sort out magnetic deposits and lightweight objects and recovering precious metals.

Further, the line may further include an M line including a step (step F) of removing metal from embrittled shredder dust of X mm or more and recovering the residue as fuel. In this case, it is divided into three lines as a whole, and an example of the overall flow is shown in FIG.

In this embodiment, in step B, the embrittled shredder dust is screened into X mm or more and less than X mm (X = 2 to 10). After sieving, it is divided into embrittled shredder dust under a sieve of less than X mm and embrittled shredder dust on a sieve of X mm or more. Is subjected to step F.

When X is 5 to 10, in order to improve the accuracy in the sorting step, the embrittled shredder dust under the sieve may be further separated into Y mm or more and less than Y mm (Y = 2 to 5) and subjected to the subsequent step C. preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
First, 2514 kg of automobile shredder dust (ASR) was prepared and slaked lime was added. Next, the ASR was charged into an Antler kiln heated to 320 ° C. at a charging rate of 30 kg / h to perform heat embrittlement treatment. After the treatment, 1961 kg of embrittled shredder dust was obtained.

Of the fragile shredder dust obtained as described above, 1889 kg is put into a magnetic force sorting device (suspended type) and then a sieving device having a 5 mm mesh (vibration sieve), and is 5 mm or more (on the sieve). ) And those less than 5 mm (under the sieve) (H line in FIG. 3).

Next, for the embrittled shredder dust of less than 5 mm under the sieve, magnetic deposits and lightweight objects were removed using a magnetic force sorting device (suspended type) and a wind force sorting device (internal circulation type) (FIG. 3). A line). Next, a heavy product that can be sufficiently used as a raw material for precious metals (gold, silver) and copper was recovered by an air table (manufactured by TRIPLE / S DYNAMICS, INC. (USA)). In particular, the gold recovery rate reached 75%. The recovered metals and their masses are shown in Table 1 below.

On the other hand, for the embrittled shredder dust of 5 mm or more on the sieve, first, metals other than iron were removed by manual sorting. Next, magnetic force sorting and sieving sorting (30 mm) were performed, and non-ferrous metals such as aluminum and copper were removed by an eddy current sorting device (rotating magnet type, rotation speed 3000 rpm) both above and below the sieve. Further, manual sorting was performed to obtain a residue (M line in FIG. 3). The residue is for use as fuel. The obtained non-ferrous metal is not large in the amount recovered, but it can be further recovered from the product after the manual sorting and magnetic force sorting in the previous process, and it has a sufficient concentration as a recycled raw material. , The recovery rate of non-ferrous metals as a whole could be increased. Furthermore, silver also had a relatively high concentration and a high recovery rate.

The sorting residue obtained on the M line and the light products, light products, and cyclondast (see FIG. 2) after wind sorting obtained on the A line are combustible (predetermined) with respect to pulverized coal, which is the main fuel of the cement kiln. In order to evaluate the rate of weight loss when burning for hours), a combustion test was carried out using a tubular electric furnace (diameter 42 mm, temperature 1450 ° C., atmospheric gas flow rate 1 L / min, test volume 1 g). The weight loss rate after the combustion test is shown in Table 2 below. While the weight loss rate of pulverized coal continued to increase in 0.5 to 4 minutes, there was almost no change in any of the embrittled solids in 0.5 to 4 minutes, and the combustibles were almost burned in 0.5 minutes. I decided that I was doing it. From the above results, it was confirmed that the embrittled solid matter has good flammability with respect to pulverized coal and can be used as a coal alternative fuel in terms of flammability without any problem. The recovered amount obtained by sorting is shown in the recovered amount column of Table 2 below.

(Example 2)
First, 650 kg of automobile shredder dust (ASR) was prepared, and wood chips and slaked lime were added. The ratio of ASR to wood chips was 70:30. Next, the ASR was charged into an Antler kiln heated to 325 ° C. at a charging rate of 30 kg / h to perform heat embrittlement treatment. After the treatment, 520 kg of embrittled shredder dust was obtained.

Of the embrittled shredder dust obtained as described above, 510 kg was put into a hammer-type crusher equipped with a screen having a mesh of 8 mm to perform a crushing treatment. After the treatment, 510 kg of embrittled shredder dust having a maximum particle size of 8 mm or less was obtained. In this embrittled shredder dust, the proportion of particles having a particle size range of 0.5 to 5 mm exceeded 60% by weight.

When the particles were put into a hammer-type crusher equipped with a screen having a 5 mm sieve and crushed, many particles having a particle size of 0.5 mm or less were found, and it is considered that the precious metal was also finely crushed. , Judged unfavorable. The particle size distribution before and after crushing is shown in Table 3 below.

505 kg of embrittled shredder dust after crushing is used as a magnetic material (No. 1 magnetic product in Table 4) and fuel as an iron raw material using a magnetic force sorting device (hanging type) and a wind force sorting device (internal circulation type). Lightweight materials (wind-selected dust in Table 4) that can be used as a magnet were removed. Next, a magnetic deposit (No. 2 magnetic product in Table 4) was removed as an iron raw material using a magnetic force sorting device (suspended type). Then, by the air table (manufactured by TRIPLE / S DYNAMICS, INC. (USA)), heavy products that can be sufficiently used as raw materials for precious metals (gold, silver) and copper, and further usable as raw materials for fuel and copper, or further added. The middle products and light products that can be used as fuel were collected through the sorting process. The recovery rates for gold, silver and copper reached 61%, 47% and 74%, respectively. The recovered metals and their masses are shown in Table 4 below. It can be seen that the recovery rate of silver and copper was significantly improved in Example 2 in which the total amount of embrittled shredder dust was X mm or less without providing the M line as compared with Example 1 in which the M line was provided. ..

Claims (5)

Step A, in which the shredder dust is heat-treated at a temperature of 250 to 400 ° C. to embrittle it to obtain embrittled shredder dust containing a resin,
Step B to make the embrittled shredder dust less than X mm (X = 2 to 10),
Step C of removing the magnetic deposit from the embrittled shredder dust of less than X mm by the magnetic force sorting means,
From the embrittlement shredder dust removing the magnetically attracted material, seen including a step D of recovering precious metals as heavy product by an air table, a,
The step B further includes step F of separating the embrittled shredder dust of less than X mm and the embrittled shredder dust of X mm or more, removing the metal from the embrittled shredder dust of X mm or more, and recovering the residue as fuel. ,
A method for recycling shredder dust, which comprises removing metal from the embrittled shredder dust of X mm or more in step F by eddy current sorting to recover nonferrous metals. The method for recycling shredder dust according to claim 1, wherein in step B, the embrittled shredder dust is crushed to make the total amount less than X mm. In the shredder dust recycling method according to claim 1 or 2, the embrittled shredder dust from which the magnetic substance has been removed in step C is divided into a plurality of particle groups having different particle size ranges and subjected to the step D. A characteristic shredder dust recycling method. The shredder dust recycling method according to any one of claims 1 to 3, wherein the shredder dust in step A is mixed with woody powder or crushed material when the shredder dust is heat-treated. How to recycle dust. The shredder dust recycling method according to any one of claims 1 to 4, further comprising a step E of recovering a recovered product other than the heavy products recovered by the air table in the step D as fuel. How to recycle shredder dust.

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