JP3512310B2 - Plastic electrostatic sorting method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sorting method in an electrostatic sorting device for sorting crushed dust made of plastic such as municipal waste and oversized waste. [0002] In a conventional electrostatic sorting apparatus, no consideration is given to humidity in the apparatus at the time of sorting, and no countermeasure is taken. [0003] In sorting plastics using static electricity, the amount of charge (the amount of charge) of the plastic is important. However, as described above, since the plastic sorting device at the time does not take measures against humidity, when the humidity is high, the surface resistance of the plastic becomes small, and not only the charge amount but also the charge holding time becomes short. (Charge escapes faster), resulting in a problem that the sorting ability is reduced. Accordingly, an object of the present invention is to provide a plastic electrostatic sorting method which improves the sorting performance by controlling the humidity in the apparatus. [0005] [Means for Solving the Problems] To achieve the above object, a plastic electrostatic sorting method according to claim 1, wherein of the present invention, the band to be sorted crushed waste of plastic
In addition to using a triboelectric charging device to
In the sorting device for sorting the used crushed refuse, a metal drum electrode and a high-voltage electrode used for sorting the crushed refuse to be sorted are provided on the upper part of the box and the internal temperature is 70 ° C. or more. , 10
In the friction charging device set at 0 ° C. or less, the selected crushed refuse is charged, and the charged crushed crushed trash is subjected to an atmosphere humidity condition of 60% or less in relative humidity. It is characterized by sorting in a box. [0008] According to the above method, the humidity in the sorting device is set to 6
By setting the temperature to 0% (relative humidity) or less, the sorting ability is maintained, and by increasing the internal temperature of the frictional charging device, the friction time for obtaining a selectable charge amount is shortened. Thereby, the sorting operation efficiency is improved. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a plastic electrostatic sorting apparatus according to an embodiment of the present invention in consideration of humidity . The crushed and sorted refuse 1 made of crushed and sorted plastic is charged by a frictional charging device 2,
It is rotated in a predetermined direction around the horizontal axis through the supply tray 3 and is spread on the upper surface of the metal drum electrode 4 that is grounded. An arc-shaped high-voltage electrode 5 parallel to the curved surface of the metal drum electrode 4 is provided diagonally above the metal drum electrode 4 in the rotation direction. Is connected. High-voltage power supply 6
Is grounded. Below the metal drum electrode 4, there is provided a first separation container 7 which opens upward at a position in front of the metal drum electrode 4 (upstream in the rotation direction).
At the position, a second separation container 8 opened upward is provided. Further, a brush 9 for scraping off the sorted crushed dust 1 is provided at a downstream position in the rotation direction of the metal drum electrode 4 (above the second separation container 8). Further, the supply tray 3, the metal drum electrode 4, the high voltage electrode 5, the first separation container 7, the second separation container 8,
The brush 9 is housed in a box 10. In the box 10, a humidity sensor 11 for detecting the relative humidity in the box 10 is provided.
Is provided with a dehumidifier 12 that operates so that the relative humidity in the box 10 detected by the above becomes the set humidity. The operation of the above configuration will be described. First, the sorted crushed dust 1 made of plastic to be sorted is charged by the friction charging device 2. At this time, the plastic is charged to either plus or minus according to the charging sequence depending on its type. The charged and sorted crushed dust 1 is cut out through the supply tray 3 to the upper surface of the rotating metal drum electrode 4. When the charged code obtained by the triboelectric charging has the same code as that of the metal drum electrode 4, the cut out sorted and crushed dust 1 is repelled, attracted to the opposing high-voltage electrode 5 , falls, and falls, and the first separation container 7. Will be collected. When the charging code is different from that of the metal drum electrode 4, the sorted crushed dust 1 is attracted to the metal drum electrode 4, and the sorted crushed dust 1 adsorbed to the metal drum electrode 4 is rotated by the rotating brush 9. Scraped off, the second separation container 8
Will be collected. Further, the relative humidity in the box 10 is maintained at the set humidity of the dehumidifier 12 by the dehumidifier 12. FIG. 2 shows the selection results of PVC when the above operation is performed by changing the set humidity of the dehumidifier 12. The recovery rate shown in FIG.
It shows the percentage of C, and the separation rate is close to 80% up to a humidity of 60%, but the recovery rate gradually decreases when the humidity exceeds 60%, and the recovery rate decreases when the humidity reaches 70%. Is reduced to 40%. From the results of the sorting, it is necessary to set the relative humidity to 60% or less in order to obtain a high sorting ability as a sorting condition for plastics. By setting the relative humidity in the box 10 to 60% or less, a high sorting ability can be obtained. In the above embodiment, the relative humidity in the box 10 is maintained by the dehumidifier 12.
Not limited to this, any means capable of maintaining humidity may be used. Further, instead of the relative humidity, an absolute humidity may be detected and the absolute humidity may be maintained. FIG. 3 shows an embodiment in which temperature is considered in addition to humidity . The implementation in the form of this, in addition to the configuration of FIG. 1, a heater 13 is wound around the outer circumference of the frictional charging device 2, a temperature sensor for detecting the internal temperature of the frictional charging device 2 (e.g., thermocouple etc.) 14 And a heater power supply device 15 for controlling a current flowing through the heater 13 so as to maintain the internal temperature of the frictional charging device 2 detected by the temperature sensor 14 at a set temperature. According to the above configuration, similarly to the operation of the configuration shown in FIG. 1, the sorted crushed dust 1 is separated and collected in the first separation container 7 and the second separation container 8, and the relative humidity in the box 10 is removed by the dehumidifier 12. Is maintained at the set humidity of the dehumidifier 12, the heater power supply 15 supplies electricity to the heater 13, and the internal temperature of the frictional charging device 2 is maintained at the set temperature of the heater power supply 15. FIG. 2 shows the result of the selection of PVC when the above operation is performed by changing the set temperature of the heater power supply device 15. The characteristics indicated by black circles are characteristics when the set temperature of the heater power supply device 15 is set to 70 ° C., and the characteristics indicated by white circles are characteristics when the heater 13 is set to room temperature without energizing the heater 13. As shown in FIG. 2, it can be seen that the recovery rate increases at a relative humidity of 60 to 70%. FIG. 4 shows the result of the friction time required to reach a selectable charge amount in the friction charging device 2 when the set temperature of the heater power supply device 15 is changed. As shown in FIG. 4, it can be seen that the friction time can be reduced by several tens of percent by setting the internal temperature of the frictional charging device 2 to a high temperature (100 ° C.). The internal temperature of the frictional charging device 2 is 100
If the temperature exceeds ℃, the melting and softening of the plastic starts to occur, so the upper limit is 100 ℃. The optimum internal temperature of the frictional charging device 2 is 70 to 100 ° C. As described above, by setting the internal temperature of the frictional charging device 2 to a high temperature, a high sorting ability can be obtained, the friction time can be reduced, and the sorting operation efficiency can be improved. In the embodiment in which the temperature is taken into consideration in addition to the humidity, the heater 13 is used to raise the internal temperature of the frictional charging device 2. Any means such as a supply mechanism for raising the internal temperature of the frictional charging device 2 may be used. As described above, according to the present invention, the sorting ability can be maintained by setting the humidity in the apparatus to 60% (relative humidity) or less, and the sorted plastic crushed refuse can be stably sorted. It can be performed. In addition, the friction charging device
High sorting ability by setting the part temperature to 70-100 ° C
Power to obtain a selectable charge amount.
The rubbing time can be shortened, thus the sorting work efficiency
Can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a plastic electrostatic sorting device according to an embodiment of the present invention in consideration of humidity . FIG. 2 is a view showing characteristics of a relative humidity and a recovery rate of the plastic electrostatic sorting apparatus. FIG. 3 is a configuration diagram of a plastic electrostatic sorting apparatus according to an embodiment of the present invention in which temperature is considered in addition to humidity . FIG. 4 is a diagram showing characteristics of friction time and charged voltage when the internal temperature of the friction charging device of the plastic electrostatic sorting device is changed. [Description of Signs] 1 Sorted crushed dust 2 Charging device 3 Supply tray 4 Metal drum electrode 5 High voltage electrode 6 High voltage power supply 7 First separation container 8 Second separation container 9 Brush 10 Box 11 Humidity sensor 12 Dehumidifier 13 Heater 14 Temperature sensor 15 Heater power supply

Continuation of the front page (72) Inventor Hidehiko Maehata 5-3-28 Nishikujo, Konohana-ku, Osaka-shi, Japan Hitachi Zosen Corporation (56) References JP-A-8-206542 (JP, A) Special Table 6 -502121 (JP, A) Table 6 6-502123 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B03C ^7/ 00-7/12

Claims (1)

(57) [Claims] [Claim 1] Sorted crushed trash made of plastic
In addition to using a triboelectric charging device to charge,
In the sorting apparatus for sorting the used crushed refuse, the apparatus is provided above a box containing a metal drum electrode and a high-voltage electrode used in the selection of the crushed refuse, and has an internal temperature of 70 ° C. or more. , 100 ° C
The selected crushed refuse is charged by the friction charging device set as follows, and the charged crushed refuse is placed in the box of the sorting device at an atmospheric humidity condition of 60% or less. A plastic electrostatic sorting method characterized by sorting by: