JP2006159047A - Specific-gravity sorting method of mixed crushed-materials and specific-gravity sorting apparatus of mixed crushed-materials - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a specific-gravity sorting process capable of sort recovering plastics highly precisely and efficiently from mixed crushed-materials such as shredder dust. <P>SOLUTION: A specific-gravity sorting method of mixed crushed-materials consists of a step wherein a material to be sorted are specific-gravity sorted by a liquid cyclone sorting apparatus to be sorted to an upper-side recovered material having a lower specific gravity than a liquid medium and a lower-side recovered material having a higher specific gravity than the liquid medium, and a step wherein the upper-side recovered material is sorted by a sink and float sorting apparatus to give a floating material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a specific gravity sorting method used for general waste and industrial waste, home appliance recycling processing, etc., and in particular, mixed crushed materials such as waste plastic which are separated and collected for various kinds of mixed materials such as shredder dust and reused. The present invention relates to a specific gravity sorting apparatus.

  Among the waste discharged in large quantities, plastic waste continues to increase, and it is difficult to deal with the disposal measures. In particular, various types of plastics that cannot be sufficiently separated by disassembly before the integrated crushing of waste products are used for OA equipment and home appliances that are discarded. These plastics recovered metals after the integrated crushing. The rest is so-called shredder dust, which is a major obstacle to the formation of a recycling-oriented society, such as being incinerated or landfilled because there are few ways to reuse it.

  The plastics used in office automation equipment and home appliances are mainly the three general-purpose plastics, polypropylene (PP), polystyrene (PS), and acrylonitrile-butadiene-styrene (ABS). PVC), phenol (PF), which is a functional insulating material, polybutylene terephthalate (PBT), flame retardant PS with flame retardant function, flame retardant ABS, and the like, and the shredder dust is a mixture of these plastics Contains foreign substances such as minute metal pieces that have not been sufficiently recovered in the previous process.

  In order to sort out PP, PS and ABS which can be quantitatively secured from the shredder dust and can be easily reused, their specific gravity is PP (about 0.9), PS (about 1.05), ABS. (About 1.05), and the specific gravity of other resins and metals often exceeds 1.1, and sorting by specific gravity can be suitably used.

  However, when the selected plastics are separated into PP, ABS, and PS, and then re-molded and recycled, any physical properties (strength, elongation, etc.) are significantly reduced when any plastic is mixed with other plastics. In many cases, such waste plastics must be sorted with a very high quality.

  Therefore, as a method for sorting out such waste plastic, a float / sink sorting method, a method using a hydrocyclone, and the like have been proposed, and some have been put into practical use.

  The floatation / sink sorting method is a method in which a crushed plastic is dispersed in a liquid medium such as water, and a plastic having a specific gravity smaller than that of the medium and a plastic having a higher specific gravity can be easily separated. By using so-called heavy liquids with different specific gravity such as water, salt water, chlorinated organic solvents, or so-called pseudo heavy liquids in which solid materials such as fine ferrosilicon are dispersed, various specific gravity It is possible to easily sort the crushed plastic having a thickness (see, for example, Patent Document 1).

In the liquid cyclone method, the crushed plastic is circumferentially flowed together with the liquid medium in a cylindrical container, and particles having a specific gravity larger than that of the liquid medium and particles having a specific gravity smaller than that of the liquid medium by centrifugal force are more efficient than the above floatation / sediment sorting. Can be sorted. By selecting the specific gravity of the liquid medium appropriately in the same manner as described above, sorting with various specific gravity is possible (for example, see Patent Document 2).
JP-A-56-56246 International Publication No. WO 98/41374

  However, in floatation / sink sorting, air and liquid media such as water will affect the sorting accuracy, so the input material such as shredder dust is contaminated with contaminants such as dust. Even so, it is difficult to increase the sorting accuracy.

  Therefore, for example, even if PP is recovered from the mixed crushed material, high-purity PP cannot be obtained unless it is washed in advance and subjected to several steps of flotation / sink sorting.

  It is impractical to carry out several stages of ups and downs sorting, and the plastics collected by the currently used ups and downs sorters are difficult to use as new products, so they are only used in cascade. ing.

  On the other hand, in the method using the liquid cyclone, the specific gravity selection proceeds only in the liquid medium without being exposed to the air, so that the accuracy of the selection due to air hardly occurs. In addition, since sorting is performed by centrifugal force, it can be installed in a small space, and the amount of liquid medium to be used is smaller than that of floating / sink sorting, and a very efficient sorting operation can be realized.

  However, since sorting is performed by applying centrifugal force in the water stream, it is easily affected by slight disturbance of the water stream, and it is difficult to achieve high sorting accuracy, and it is difficult to ensure the quality necessary for recycling plastics. Furthermore, since the plastics to be regenerated are originally molded by molding, they often show a flake form even after crushing, and are susceptible to the disturbance of the water flow.

  In order to avoid this deterioration in sorting accuracy, it is necessary to finely re-pulverize the crushed material until it does not show a flake form, and to use a sieve to align the size of the particles. Since a molded product of a kind has a thickness of about 1 to 4 mm, it is necessary to pulverize below this in order not to show a flake form, and generation of a great pulverization cost and a decrease in yield are inevitable. .

  Therefore, even specific gravity sorting means such as plastic using a liquid cyclone cannot be applied to high-purity plastic recovery applications, and what is put into practical use is only for plastics that are used in cascade, as in the above-described floatation / sink sorting. .

  Cascade plastics are used as materials for daily necessities such as artificial trees that can be used at low purity and hangers that do not require durability, but because their applications are limited, a recycling-oriented society is established. In order to achieve this, there is a demand for a technology for recovering plastics with high purity from mixed crushed materials that can be used for higher level applications.

  The present invention has been made to solve the above problems, and provides a specific gravity sorting method and apparatus capable of sorting and recovering plastics with high accuracy and efficiency from shredder dust and other mixed crushed materials. With the goal.

  The specific gravity sorting method of the mixed crushed material according to the present invention performs the specific gravity sorting of the object to be sorted by the liquid cyclone sorting apparatus, and sorts the upper collected material having a lower specific gravity than the liquid medium and the lower collected material having a higher specific gravity than the liquid medium. And a step of sorting the upper collected material by a float / sink sorter and collecting the floated material.

  The specific gravity sorting method according to the present invention can sort the mixed crushed material in a wide particle size range with high precision and high efficiency by the above configuration.

Embodiment 1 FIG.
1 to 6 are diagrams showing Embodiment 1, FIG. 1 is a diagram showing a sorting process, FIG. 2 is a diagram showing a sorting process of a comparative example, FIG. 3 is a diagram showing a hydrocyclone sorting apparatus, and FIG. FIG. 5 is a diagram showing a sorting device, FIG. 5 is a layout diagram of a sorting device, and FIG. 6 is a diagram showing a sorting result.
Shredder dust generated by recycling home appliances and OA equipment was prepared as a material to be sorted. This shredder dust uses a hammer type crusher to crush various products such as home appliances and OA equipment, and then uses the magnetic sorting device and eddy current sorting device in multiple stages to collect the remainder of the metal of φ50mm. This was further pulverized by a uniaxial shear type crusher using a screen. In the first embodiment, PP is recovered from the shredder dust. When the PP component in the shredder dust is analyzed in advance, 30% is contained.

  In order to recover PP from shredder dust, a hydrocyclone sorter and a float / sink sorter using water as a liquid medium were prepared, and the sorting process was combined as shown in FIG. That is, the shredder dust is sorted by the hydrocyclone sorter in the first step, and the upper collection product to which PP is concentrated is sorted by the floatation / sink sorter in the second step, and the PP concentrate is collected as a floating product.

On the other hand, as a comparative example, the process of FIGS. 2A, 2B, and 2C was also performed to collect PP.
(A) The shredder dust is sorted by the hydrocyclone sorter in the first step, and the upper recovery product to which PP is concentrated is also sorted by the hydrocyclone sorter in the second step, and the PP concentrate is used as the upper recovery product. to recover.
(B) The shredder dust is sorted by the float / sink sorter in the first step, and the floated material to which PP is concentrated is also sorted by the float / sink sorter in the second step, and the PP concentrate is recovered as a floated product.
(C) The shredder dust is sorted by the float / sink sorter in the first step, and the floated material to which PP is concentrated is sorted by the hydrocyclone sorter in the second step, and the PP concentrate is recovered as the upper collection. .

  Here, the used hydrocyclone sorter is shown in FIG. The hydrocyclone 1 used was a body part 9 inches and a length 27 inches. In the sorting device, about 700 L of the storage water tank 2 provided with the storage water tank agitation device 4 was prepared in the lower part, and about 1% by weight of shredder dust was added to the water. This mixed water was supplied to the hydrocyclone 1 by a 15 kw slurry pump 3, and the sorted water was used as a circulation circuit that returned to the reservoir tank 2.

  That is, the object to be sorted put into the reservoir tank 2 is uniformly mixed with the liquid medium water by the reservoir tank agitator 4 and supplied to the hydrocyclone 1 through the slurry pump 3. In the hydrocyclone 1, particles having a specific gravity larger than that of the liquid medium water flow out of the lower recovery port 6 and particles having a specific gravity smaller than that of the liquid medium water flow out of the upper recovery port 5 and are sorted by specific gravity. The In the first embodiment, the recovered PP has a specific gravity smaller than that of water, and is therefore concentrated and discharged from the upper recovery port 5.

  FIG. 4 shows the float / sink sorter used similarly. The main body of the float / sink sorter is a float / sink tank 10 capable of storing 3000 L of liquid medium, and includes a supply port agitator 11 at the sorting object supply port, and a paddle 12 for stirring and transporting the float on the liquid medium. The floated sort is collected through a sieve 13 that collects the suspended matter. The liquid medium that has passed through the sieve 13 is returned to the floating and sinking tank 10 by a 2 kw pump 14. On the other hand, the sediment is transported and collected by the screw conveyor 15 to complete the sorting.

  As shown in FIG. 5, the more specific equipment arrangement of the first embodiment is such that the flow of the object to be selected and the flow of water as the liquid medium are reversed. That is, a part of the water used in the float / sink sorting is passed to the hydrocyclone sorter 22, a part of the water used in the liquid cyclone sorter 22 is passed to the water treatment device 21, and the purified water is passed to the float / sink sorter 23. used. By using the liquid medium in cascade as described above, it is not necessary to install the water treatment device 21 excessively, and the equipment cost can be kept low.

FIG. 6 shows the results of selection in the comparative example and the process in the first embodiment.
In the process according to the first embodiment, 30% PP originally contained in the shredder dust is concentrated to 70% by the hydrocyclone sorter 22 as the first step, and recovered from the upper recovery port 5. . Further, when the upper collection product is sorted by the floatation / sink sorting device 23 as the second step, the floated product concentrated to 99% or more is collected. At this time, the amount of PP in the lower collection of the hydrocyclone sorter 22 in the first step was 1% or less, and no PP was detected from the sediment in the float / sink sorter 23 in the second step. . That is, high-purity PP with a concentration of 99% or more can be recovered with high efficiency at a PP yield of 99% or more.

  On the other hand, in the comparative example (a), since the first step is the same hydrocyclone sorter 22 as in the first embodiment, an upper recovered material having the same PP concentration was obtained with the same yield. Even when the recovered material was further subjected to the hydrocyclone sorter 22 in the second step, the concentration of the upper recovered material was only concentrated to 80%. At this time, when the impurities were analyzed, most of them were PS and ABS having a specific gravity of about 1.05, and they were relatively large pieces of particles having a diameter of about 30 mm to 50 mm. That is, in the sorting by the hydrocyclone sorter 22, impurities are inevitably mixed due to the turbulence of the water flow. However, since large particles in particular are affected by this, the sorting by the hydrocyclone sorter 22 is repeatedly performed. It is also determined that PP cannot be concentrated.

  Further, in Comparative Example (b), the floatation / sink sorting was performed in the first step, and a recovered material having a concentration of 75% higher than that of the liquid cyclone was obtained. The concentration could only be increased to 85%. At this time, the characteristics of the impurity component were analyzed in the same manner as in Comparative Example (a). However, there were many relatively small particles having a diameter of 30 mm or less, and the surface of each particle remained contaminated with dust or the like. It was easy. In other words, small particles with a slow sedimentation rate in water cannot be adequately sorted by flotation and sedimentation. In the floatation / sink selection that is not exposed to a strong water flow like a cyclone, the cleaning effect is poor, and the fact that the bubbles are not sufficiently removed is considered to be the reason why the purity cannot be increased.

  Furthermore, in Comparative Example (c), floatation / sink selection was performed in the first step, and the recovered material that floated was selected using a liquid cyclone in the second step, but the PP purity of the recovered material was only 85%. Considering the reason why the purity does not increase from the knowledge so far, the apparent specific gravity of the impurities in the first step of the flotation / settlement change has changed due to small particles and bubbles adhering to contaminants such as dust. It is thought that the main thing was, but in the second step of the subsequent liquid cyclone, the impurity component due to the particle size of the former was eliminated, but the latter changed the apparent specific gravity due to contamination of the latter. Although it is washed in the inside, naturally, since it contains large pieces of particles, it is considered that these became impurities and the purity of the recovered material could not be increased.

  As described above, according to the specific gravity selection process of the present embodiment, the rough selection is performed by the liquid cyclone in the first step, and the final selection is performed by the floating / sink selection in the second step. Shredders with a relatively wide particle size range with dirt and other contaminants attached to them because they can effectively utilize the effects of high-purity sorting of relatively small particles and high-purity sorting of relatively large particles in the ups and downs. It is possible to efficiently sort specific gravity with high purity.

  In the first embodiment, shredder dust pulverized at φ50 mm was used, but high-purity and high-efficiency sorting can be performed even at φ50 mm or more, but the original shape of plastics is a shell-like molded product. In addition, since it has a deformed portion such as a rib, there is a portion that is hard to collect air and is difficult to clean, and 99% or higher purity recovery as shown in the first embodiment is impossible. It is desirable to grind into:

Embodiment 2. FIG.
In the second embodiment, in the process shown in FIG. 1 similar to the first embodiment, the salt water adjusted to a specific gravity of 1.1 is used from the residue obtained by collecting the PP discharged in the first embodiment. The PS and universal ABS mixture was recovered. In addition, as a comparative example, sorting was also performed in the process of FIG.

  In general, PS and ABS are used as main plastics in addition to PP in home appliances and OA equipment, but many of those with a specific gravity of 1.1 or more include flame retardants (such as PBDE) that are no longer used in home appliances. Even if it is collected, its use is limited. In addition to flame retardant plastics, it contains a wide variety of plastics such as PVC, PF, and other hard-curing plastics, such as PVC, PBT, etc.

  On the other hand, general-purpose PS and ABS can be expected to recover a large amount as main components, but the specific gravity of both is almost the same, and cannot be separated by specific gravity sorting. However, if only PS and ABS can be selected by specific gravity selection, it is possible to develop applications by performing electrostatic selection in a subsequent process.

FIG. 7 shows the selection result in the second embodiment. In addition, it was about 40% when the weight ratio of general purpose PS and general purpose ABS in a to-be-sorted object was measured previously.
The object to be sorted of the second embodiment has already been washed with water in the process of the first embodiment, and is relatively high regardless of whether the liquid cyclone is used in the first process or the floatation / sink sorting is used. Concentration was observed. However, the purity of 99% or more indicated by the result of Embodiment 2 could not be realized in Comparative Example (c).

  The present invention is not limited to the specific gravity selection process described in the embodiment described above and shown in the drawings. For example, a light specific gravity material such as alcohol is used as a liquid medium, ferrosilicon or the like. For example, a pseudo-heavy liquid can be used with various modifications within a range in which the gist cannot be removed.

It is a figure which shows Embodiment 1 and is a figure which shows a selection process. It is a figure which shows Embodiment 1, and is a figure which shows the selection process of a comparative example. It is a figure which shows Embodiment 1, and is a figure which shows a hydrocyclone sorter. It is a figure which shows Embodiment 1, and is a figure which shows an ups and downs sorting apparatus. It is a figure which shows Embodiment 1 and is a sorter arrangement drawing. It is a figure which shows Embodiment 1, and is a figure which shows a selection result. It is a figure which shows Embodiment 2, and is a figure which shows a selection result.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hydrocyclone, 2 Reservoir tank, 3 Slurry pump, 4 Reservoir tank agitator, 5 Upper recovery port, 6 Lower recovery port, 10 Floating / sink tank, 11 Supply port agitator, 12 Paddle, 13 Sieve, 14 Pump, 15 Screw Conveyor, 21 Water treatment device, 22 Hydrocyclone sorting device, 23 Flotation / sinking device, 24 Liquid medium flow, 25 Sorted material flow.

Claims (3)

The specific gravity of the object to be sorted is selected by a liquid cyclone sorting apparatus, and the upper recovered material having a specific gravity smaller than the liquid medium and the lower recovered material having a higher specific gravity than the liquid medium are selected.
A method for selecting the specific gravity of the mixed crushed material, comprising: a step of sorting the upper collected material by a floatation / sink sorting device and collecting the floating material.   The liquid medium used in the float / sink sorter is used in the liquid cyclone sorter, and the liquid medium used in the liquid cyclone sorter is purified and used in the float / sink sorter. Specific gravity sorting method for mixed crushed material. The object to be sorted put in the storage tank is mixed with the liquid medium by the storage tank agitator, supplied to the liquid cyclone through the slurry pump, and particles having a specific gravity larger than that of the liquid medium by the rotary motion in the liquid cyclone. A liquid cyclone sorting device that flows out from the recovery port and particles having a specific gravity smaller than that of the liquid medium flow out of the upper recovery port and is subjected to specific gravity sorting.
In addition to having a supply port agitating device at the sorting object supply port to which the upper recovery product flowing out from the upper recovery port of the liquid cyclone sorting device is supplied, it also has a paddle for stirring floating material and transporting it on the liquid medium And a specific gravity sorter for mixed crushed material, comprising: a float / sink sorter for collecting floated sort through a sieve for collecting floated matter.

Images