JP2962684B2 - Nonferrous metal sorting method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for sorting non-ferrous metals by eddy current sorting, and more particularly to a method and an apparatus for sorting non-ferrous metals for recovering high-purity non-ferrous metals from waste. .

[0002]

2. Description of the Related Art An eddy current sorter uses a repulsive force generated by electromagnetic induction when a magnet and a nonferrous metal are relatively moved to sort and recover nonferrous metals. There are two types of eddy current selection devices, a permanent magnet type using a permanent magnet as a magnet and a linear motor type using an electromagnet. Permanent magnet systems are superior in simplicity of structure and ease of maintenance, such as lower power consumption than linear motor systems using electromagnets and no need for electromagnet cooling equipment. It is the mainstream of sorting equipment.

The permanent magnet system includes a permanent magnet rotating system in which permanent magnets arranged alternately in a rotating drum are rotated,
There is an inclined plate type in which a flat plate in which permanent magnets are alternately arranged is inclined, and an object to be sorted is supplied thereon. The inclined plate type requires less power than the permanent magnet rotating type that requires electric power to rotate the permanent magnet, but the relative speed between the magnet and the non-ferrous metal is difficult to control because the non-ferrous metal rolls easily on the slope . For this reason, means for preventing rolling of the non-ferrous metal is required. Therefore, the permanent magnet rotary type is superior to the inclined plate type in that it can be selected stably and easily (Shinko Electric Technical Report 131, Vol. 37, No. 2, p. 29-36, 1992) .

[0004]

However, in the conventional permanent magnet rotary type apparatus, there is a limit in the performance for separating non-ferrous metals with high purity and high recovery rate for the following reasons. That is, the structure of the permanent magnet rotary eddy current sorter is as shown in FIG. 9, and the electromagnetic force acting on the non-ferrous metal piece 2000 in the sorter is proportional to the following three factors.

[0005] 1. 1. Magnetic flux density on the surface of the rotating drum 101 and pitch interval between the magnets 601 2. Relative speed between magnet 601 and non-ferrous metal piece 2000 The volume of the non-ferrous metal piece 2000 One of the magnetic flux density and the pitch interval is determined by specifications at the time of design. The relative speed between the second magnet and the non-ferrous metal piece is determined by the rotation speed of the rotating drum 101 on which the magnets are arranged and the relative speed between the non-ferrous metal 2000 conveyed on the conveyor belt 102 and the operating conditions. Can be changed by

However, the volume of the non-ferrous metal pieces (3), especially in the case of waste, greatly varies depending on the type of the object to be sorted, and the range of the variation is larger than the adjustment range of (1) and (2). . For example, the magnetic flux density of a normally used permanent magnet is in the range of about 3,000 to 5,000 gauss, and the relative speed between the magnet and the non-ferrous metal piece is preferably as large as possible. It fluctuates.

On the other hand, the volume of a non-ferrous metal piece has a width ranging from several millimeters to several hundreds of millimeters, and considering that the volume is proportional to its cube, the magnetic flux on the rotating drum surface of 1. The variation range is much larger than the density or relative speed between the magnet and the non-ferrous metal piece in 2. As a result, the current eddy current sorter is greatly affected by the particle size distribution of the waste to be sorted, and even if the specifications and operating conditions of the equipment are changed, the one with a small particle size and the one with a large particle size are changed. At the same time, sorting cannot be performed with high efficiency.

Further, for example, as a means for increasing the magnetic flux density on the surface of the rotating drum, there is a method of increasing the magnetic flux density of the magnets in the rotating drum or a method of reducing the pitch between the magnets. However, in the method of increasing the magnetic flux density, since a ferromagnetic magnet is used as compared with the conventional method, not only is it expensive, but also the force with which the mixed magnetic material adheres to the rotating drum increases, making it difficult to scrape off. Become.

[0009] For this reason, the magnetic material tends to adhere to and accumulate on the rotating drum to block the inside of the sorting machine or to wear the belt. On the other hand, in the method of reducing the pitch, the magnetic flux density becomes weaker because the thickness of the magnet becomes smaller,
There is a limit.

There is also a method of increasing the recovery rate by changing the operating conditions. For example, when the relative speed between the magnet and the non-ferrous metal piece is increased, the recovery rate of the non-ferrous metal increases.
The purity decreases due to an increase in nonmetal contamination. Similarly,
There is also a method of increasing the recovery rate of the non-ferrous metal by bringing the position of the divider closer to the rotating drum, but this also increases the non-metal contamination and lowers the purity.

According to the present invention, an irregular non-ferrous metal material having a large particle size distribution can be easily obtained without depending on only the operating condition such as the specification of the magnetic flux density and the relative speed between the magnet and the non-ferrous metal. An object of the present invention is to provide a method and an apparatus for sorting non-ferrous metals which can be sorted and recovered at a high purity and a high recovery rate.

[0012]

Means for Solving the Problems As a result of detailed examination of the limit of the sorting performance of the conventional apparatus, the inventor paid attention to the fact that the sorting performance depends on the particle size. Can be sorted and recovered with high purity and a high recovery rate.

(1) The objects to be sorted are classified by a sieve according to the particle size, and eddy currents are sorted according to the particle size classification. At this time, the smaller the particle size category, the larger the relative speed between the rotating drum and the conveyor belt, the smaller the divider distance as operating conditions, and the larger the magnetic flux density on the rotating drum surface of the eddy current sorter as equipment specifications. By reducing the pitch interval of the magnets, or by setting at least one of these, a large electromagnetic repulsion is exerted on non-ferrous metals having a small particle size range, and non-ferrous metals are separated from other non-metals by a high level. It can be sorted and recovered with high purity and high recovery rate.

(2) As means for realizing the above item 1, a sieve for classifying the particle size of the object to be sorted, switching means for switching the timing of supplying the object to be sorted to the sorting machine for each particle size classification, By providing a switching control means to be operated and a sorter control means for changing the operating condition of the eddy current sorter according to the supplied particle size classification by a signal from the switching control means, By exerting a large electromagnetic repulsion on non-ferrous metals, non-ferrous metals can be sorted and recovered from other non-metals with high purity and high recovery rate.

(3) The eddy current sorter of the above 2 is provided with at least one of a rotating drum having a variable number of rotations, a conveying belt having a variable speed, and a divider whose position can be adjusted.
This makes it possible to output a signal from the switching control means to keep the eddy current sorter under appropriate operating conditions in accordance with the particle size distribution being supplied, and to provide a large electromagnetic repulsion for non-ferrous metals having a small particle size. Force can be applied, and non-ferrous metals can be sorted and recovered from other non-metals with high purity and high recovery rate.

(4) As means for realizing the above item 1, the non-ferrous metal sorting apparatus is constituted by a sieve for classifying the particle size of an object to be sorted, and an eddy current sorter provided with a partition plate along a belt conveying direction. According to the eddy current sorter, depending on the path generated by the partition plate, i) a magnet having a different magnetic flux density on the drum surface is arranged on the rotating drum portion, ii) a particle size of the sorter, By providing a divider at a position corresponding to the classification or by providing at least one of them, a large electromagnetic repulsion is exerted on non-ferrous metals having a small particle size, and non-ferrous metals are separated from other non-metals with high purity and high purity. It can be sorted and collected at a high recovery rate.

(5) By setting the sieve size of the above-mentioned sieves 1 to 4 to a predetermined value in the range of 10 mm to 50 mm, it is possible to effectively reduce the incorporation of foreign substances other than non-ferrous metals. .

Also, in the present invention, attention is paid to the fact that the electromagnetic force acting on the non-ferrous metal in the eddy current sorter under a certain condition is proportional to the apparent volume B and the filling rate η of the non-ferrous metal piece defined by the equation (1). did.

[0019]

Η = η / B (1) (where Α = actual volume B = apparent volume) Therefore, by the following means, the particle size is relatively large, the voids are small in shape, and the packing ratio is large. High quality non-ferrous metal pieces can be sorted and collected.

(6) By providing at least one of the recovery hoppers at a position farther from the rotating drum of the eddy current sorter along the traveling direction of the sorting object, the non-ferrous material having a relatively large particle size and a small gap is provided. Metal can be recovered.

According to the present invention, the sorting object is classified by a sieve according to the particle size, and the magnetic flux density on the rotating drum surface, the magnet and the non-ferrous metal, so as to exert a large electromagnetic repulsive force on the non-ferrous metal having a small particle size. Non-ferrous metals can be sorted and recovered with high purity and a high recovery rate by changing the conditions such as the relative speed between the pieces and the like and applying them to an eddy current sorter.

The electromagnetic force acting on the non-ferrous metal in the eddy current sorter under a certain condition is determined by the apparent volume B of the non-ferrous metal.
The non-ferrous metal piece having a relatively large particle size and small voids is subjected to a large force both vertically upward and in the direction of the conveyor belt in the sorting machine because it is proportional to the filling rate η. Therefore, by providing at least one of the collecting hoppers at a position farther from the rotating drum of the eddy current sorter along the traveling direction of the sorting object, the non-ferrous metal having a relatively large particle size and a small amount of voids is collected. can do.

[0023]

1 to 9 show an embodiment of the present invention.
This will be described with reference to Tables 1 and 2.

FIG. 4 is a flowchart showing an embodiment of the sorting method according to the present invention. The method includes a sieving step using a sieve 2 and a sorting step using eddy current sorters 11 and 12. The raw material 20 is first divided by the sieve 2 into two according to the particle size.

The sieved large particle 21 and small particle 22 are separated into non-ferrous metals and non-metals by eddy current sorters 11 and 12, respectively. Table 1 shows the conditions of the eddy current sorters 11 and 12.
As shown in Category 1 of the operation, the operating conditions are to increase the relative speed between the rotating drum and the conveyor belt or to reduce the divider distance in comparison with the large particle size in the small particle size category.
Set at least one.

As for the equipment specifications, the magnetic flux density of the magnet should be increased in the small particle size section compared with the large particle size so that the non-ferrous metal piece having a small particle size receives a large repulsive force.
Alternatively, the pitch interval is reduced, or one of the designs is adopted. In addition, about the said operating conditions and equipment specifications,
It is not necessary to set both, and only the operating conditions or the device specifications may be set.

[0027]

[Table 1]

FIG. 3 is a conceptual diagram showing one embodiment of the sorting apparatus of the present invention. The apparatus comprises a sieve 2, a supply hopper 30 having a switching means 31, a switching control means 41, a sorting machine control means
42, comprising an eddy current sorter 1. The raw material 20 is previously divided into two by a sieve 2 according to the particle size.

Subsequently, the large particle 21 and the small particle 22 are put into each section of the supply hopper 30 whose inside is partitioned by a partition plate 32, and the switching means 31 provided at the outlet of the hopper outputs a particle size separation. Is supplied to the eddy current sorter 1 alternately every time. The operation of the switching means is performed by a switching signal from the switching control means 41.

It is preferable that the switching signal is operated at predetermined time intervals by a timer incorporated in the switching control means. Further, the switching control means 41 also sends a signal notifying the switching timing of the switching means 31 to the sorting machine control means 42. Then, the sorter control means 42 outputs a signal for changing the operating condition in conjunction with the switching so that the operating condition of the eddy current sorter is maintained at an appropriate condition according to the particle size classification. Send to

In this way, the objects to be sorted are sorted according to the particle size classification under appropriate operating conditions. As shown in section 2 of Table 1, the operating conditions of the rotating drum and the conveyor belt in the small-diameter section are larger than those in the large-diameter section so that even non-ferrous metal pieces having a small particle diameter receive a large repulsive force. , Or at least one of them is changed.

The time interval of the switching signal from the switching means 41 is not limited to the above, but means for detecting at least one of the weight and the volume of each of the large particle size side and the small particle size side in the supply hopper. It is sufficient to switch according to the detected value so that the respective sorting objects in the large particle size section and the small particle size section are smoothly sorted without staying in the supply hopper 30 unevenly. In this method, it is only necessary to add a feed hopper and control means with a built-in sieve and switching means to the existing conventional sorting apparatus, and it is simple with a small installation area, and with higher purity and higher recovery than the conventional one. Metal can be sorted.

FIGS. 1 and 2 are a flow chart showing an embodiment of the apparatus of the present invention and a perspective view thereof. This apparatus comprises an eddy current sorter 1 having a sieve 2 and a partition plate 500.
Consists of three. The raw material 20 is previously divided into at least two or more particles by a sieve 2 and supplied to an eddy current separator 13 from a supply unit 50.

In the eddy current sorter 13, the path of the raw material on the conveyor belt 102 is divided by a partition plate along the traveling direction of the conveyor belt.
The paths are divided by 500, and dividers 103 and 104 whose positions can be adjusted are provided in the sorting section of each divided path.

The large particle 21 and the small particle 22 obtained by sieving the raw materials
Flows through each of the transport paths separated by the partition plate 500, and is separated and collected into non-ferrous metals and non-metals for each particle size classification.

The operating conditions at this time are as follows:
As shown in the figure, the divider 10
The distance between the rotary drum 101 and the rotary drum 101 is set smaller than the distance between the divider 103 and the rotary drum 101 for sorting large-diameter particles. The non-ferrous metal and the non-metal are sorted and collected for each particle size by setting at least one of the magnetic flux density and the pitch interval to be small. According to this method, high-purity and high-efficiency sorting can be performed at high speed with a compact facility. Reference numeral 108 in FIG. 4 denotes a conveyor belt driving drum rotated by a motor, and 111, 112, and 114 all denote hoppers.

The sieve diameter of the apparatus of the present invention is 10 to 50 mm
Good degree. Further, the shape of the sieve includes a lattice shape and a circular shape, and is not particularly limited. Hereinafter, the basis of the above sieve diameter will be described.

First, it will be described that it is difficult to sort non-ferrous metals with high purity and high recovery rate by using the current apparatus when targeting wastes or the like having a large particle size distribution.

Table 2 shows the test results of an eddy current sorter of a fixed specification, in which only the operating conditions were changed. In other words, in an eddy current sorter having a rotating drum diameter of 314 mm, a magnetic flux density of 3,000 gauss, and a pitch interval of 60 mm, the rotating drum rotation speed among the operating conditions is the maximum 2500 rpm of the device, and the position of the divider is horizontal from the top of the rotating drum. It is an example of the result of the recovery rate of non-ferrous metals and non-metals when it is fixed to 350 mm and 140 mm vertically downward and the belt speed of the conveyor belt is changed to 70,88,106 m / s. Here, in the apparatus used, the traveling directions of the rotary drum and the conveyor belt are opposite, so that when the belt speed is low, the relative speed between the rotary drum and the conveyor belt is low. The sorting target is non-ferrous metal and non-metal mixed waste with a particle size in the range of 2 to 200 mm.

According to Table 2, the belt speed was increased from 70 m / s to 106 m / s.
The recovery of non-ferrous metals increased from 79% to 93%, while the recovery of non-metals decreased from 100% to 71%. At an intermediate belt speed of 88 m / s, the recovery of non-ferrous metals and non-metals is 84% and 89%, respectively. The non-ferrous metal and the non-recovered portion of the non-metal are mixed into the opposite side as impurities. In this way, the system can reduce non-ferrous metals and non-metals in waste by 90% even when operating conditions are changed.
It is difficult to sort at the above recovery rates.

Therefore, as a result of examining the recovery at this time for each particle size, the causes of the performance limitations are as follows: 1) the recovery of non-ferrous metals is remarkably reduced in the range where the particle size is relatively small;
2) It was found that as the particle size increases, the recovery rate of nonmetals decreases. That is, as shown in FIG. 5, when the belt speed is low at 78 m / s, the recovery rate of the non-ferrous metal is within a range of about 20 mm or less as shown in FIG. 106m / s with low belt speed
Then, the recovery of non-metals having a particle size of 20 mm or less can be slightly improved, but the recovery of non-metals having a particle size of 30 mm or more starts to decrease.

These can be explained as follows. That is, regarding the above 1), the change in the particle size is more affected by the electromagnetic force acting on the non-ferrous metal pieces than the device specifications such as the magnetic flux density and pitch interval on the rotating drum surface and the operating conditions such as the relative speed between the rotating drum and the conveyor belt. Since this greatly affects the force, the recovery rate decreases when the particle diameter becomes small. Further, the following can be considered as the cause of the above 2). That is, non-metals with large grain size
When it falls from the conveyor belt to the hopper, it falls in a parabola according to the inertial force conveyed by the belt, and its track has a width corresponding to the particle diameter. On the other hand, in the case of non-ferrous metal with a small particle size, the repulsion force received is small, so the range of change of the track due to the electromagnetic force is small, and the track changed by the electromagnetic force is the track of the non-metal with a large particle size. Is included in the range. For this reason, it becomes difficult to sort by the flight distance.

[0043]

[Table 2]

Therefore, if the particle size of the raw material is classified and selected under appropriate conditions, the non-ferrous metal can be recovered with high purity and a high recovery rate even with the current equipment specifications. In other words, the particle size of the raw material is sieved at, for example, 20 mm.At this time, for those having a particle size of 20 mm or less, non-ferrous metals having a particle size of 2 mm and non-metals having a particle size of 20 mm can be selected without being mixed with each other. If the non-ferrous metal having a particle size of 20 mm and the non-metal having a particle size of 200 mm can be sorted without being mixed with each other, the whole can be sorted with high efficiency. FIGS. 6 and 7 show comparative analysis of tracks of a non-ferrous metal having a particle diameter of 2 mm and a non-metal having a diameter of 20 mm, and tracks of a non-ferrous metal having a particle diameter of 20 mm and a non-metal having a diameter of 200 mm in the eddy current sorter 1 having the above specifications. It was done.

However, here, the divider was removed in order to examine the track. Particles flowing on the conveyor belt 102 are caused by the inertial force in the conveying direction in the case of non-metal, and by the effect of electromagnetic repulsion acting by the relative speed between the belt and the rotating drum 101 in the case of non-ferrous metal. Follow the tracks inside. By providing the tips of the dividers 104 and 103 in the shaded regions in FIGS. 6 and 7, non-ferrous metals and non-metals can be sorted with high purity and high recovery.

In the example shown here, the particle size distribution of the raw material is 2
Actually, for example, when crushing waste and sorting it, the particle size distribution differs depending on the type of raw material waste, and when the particle size is small, the particle size is 1 to 200 mm.
When the particle size is large, it is about 5 to 500 mm. In consideration of these, the above-mentioned raw material particle size distribution 2 to 200 m
In consideration of the same ratio, referring to the fact that a high screening efficiency was obtained with a sieve diameter of about 20 mm for m, as a suitable diameter of the sieve, a predetermined size within a range of approximately 10 m to 50 mm It is desirable to set.

FIG. 8 is a side view showing an embodiment of the apparatus of the present invention. Since the electromagnetic force acting on the non-ferrous metal in the eddy current sorter under a certain condition is proportional to the apparent volume B and the filling rate η of the non-ferrous metal piece defined by the above equation 1, it has been carried on the conveyor belt 102. Non-ferrous metal particles having a large particle size, a small void, and a high filling rate receive a greater force both vertically upward and in the direction of the conveyor belt. As a result, the non-ferrous metal A having a large particle size, a small void, and a high filling rate is higher than the conveying belt surface and flies to a far position. Therefore, in addition to the usual divider 204, by providing the divider 203 at a position farther from the rotating drum of the eddy current sorter along the traveling direction of the sorting object, the hopper 117 is moved at the track B in the normal drawing. Than the recovered non-ferrous metals,
High-quality non-ferrous metal having a large particle size, a small amount of voids, and a high filling rate can be selectively collected by the hopper 116 via the track A.

[0048]

According to the method and the apparatus of the present invention, non-ferrous metals can be highly purified and recovered by sieving the objects to be sorted according to the particle size and setting eddy currents under appropriate conditions. Can be sorted and recovered from non-metals at a high rate

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the apparatus of the present invention.

FIG. 2 is a perspective view showing an embodiment of the apparatus of the present invention.

FIG. 3 is a conceptual diagram illustrating an embodiment of a sorting device according to the present invention.

FIG. 4 is a flowchart illustrating an embodiment of a sorting method according to the present invention.

FIG. 5 is a graph showing a test result of a change in a recovery rate according to a particle diameter.

FIG. 6 is a graph obtained by measuring and analyzing a track of an object to be sorted in an eddy current sorter.

FIG. 7 is a graph obtained by measuring and analyzing a track of an object to be sorted in an eddy current sorter.

FIG. 8 is a side view showing an embodiment of the apparatus of the present invention.

FIG. 9 is a schematic view showing the structure of a permanent magnet rotary eddy current sorter.

[Explanation of symbols]

1 ... Eddy current sorter, 2 ... Sieve, 11 ... Eddy current sorter, 12 ... Eddy current sorter, 13 ... Eddy current sorter, 20 ... Raw material, 21 ... Large grain size, 22 ... Small grain size, 30 ... supply hopper, 31 ... switching means, 32
... partition plate, 41 ... switching control means, 42 ... sorting machine control means,
50: supply means, 101: rotating drum, 102: transport belt, 10
3 ... divider, 104 ... divider, 105 ... supply unit, 106 ... iron scraping means, 108 ... conveyor belt drive drum, 110 ... hopper, 111 ... hopper, 112 ... hopper, 113 ... hopper, 114 ... hopper, 203 ... divider , 204: Divider, 500: Partition plate, 601: Magnet, 603: Divider, 2000: Non-ferrous metal piece.

(72) Inventor Chihiro Fukumoto 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Inside Hitachi, Ltd. (72) Inventor Tatsuya Koizumi 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Inside Hitachi, Ltd. (56 References JP-A-51-87663 (JP, A) JP-A-9-75773 (JP, A) JP-A-58-48343 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB Name) B03C 1/00-1/32

Claims (4)

(57) [Claims] 1. An eddy current separator for separating an object to be sorted into non-ferrous metals and other substances by eddy current, means for supplying a previously crushed object to the eddy current separator, and the eddy current sorting In a non-ferrous metal sorting apparatus comprising means for collecting sorted materials sorted by a machine, means for sorting the objects to be sorted into a predetermined range of particle diameters before introducing them to an eddy current sorter, and the sorting means Switching means for switching the timing of supplying the separated objects of each of the divided particle size categories to the eddy current sorter, and switching control means for operating the switching means,
A non-ferrous metal sorting apparatus, comprising: a sorter control means for changing an operating condition of the eddy current sorter in accordance with a particle size classification of an object to be sorted according to a signal from the switching control means. 2. A ferrous metal sorting apparatus as claimed in claim 2, a rotary drum having a built-in permanent magnet, a conveyor belt to transport toward the rotating drum to be sorted matter, the flight distance due to the electromagnetic force from the rotating drum An eddy current sorter comprising a divider that distinguishes non-ferrous metals and other substances according to the difference between the number of rotations of the rotary drum, the feed speed of the conveyor belt, and the position of the divider, at least one of the objects to be sorted. 1. A non-ferrous metal sorting apparatus comprising means for changing the size of a non-ferrous metal according to the particle size classification of the non-ferrous metal. 3. A rotating drum having a built-in permanent magnet, a conveyor belt for transporting an object to be sorted toward the rotating drum, and a non-ferrous metal and another substance are distinguished by a difference in a flight distance due to an electromagnetic force from the rotating drum. An eddy current sorter comprising a divider, a means for supplying a previously crushed material to the eddy current sorter, and a non-ferrous metal sorting device comprising means for collecting the sorted material sorted by the eddy current sorter. Means for classifying the objects to be sorted into a predetermined range of particle diameters before being introduced into the eddy current sorter; A partition plate provided along the feed direction on the conveyor belt so as to be transported on the conveyor belt of the vortex separator, and a divider capable of adjusting a position in accordance with each particle size division are provided. Nonferrous metals sorting apparatus. 4. The method according to claim 4, wherein the magnetic flux density on the surface of the drum is different according to the particle size of each of the objects to be sorted which are transported by being separated on the conveyor belt of the eddy current sorter by a partition plate. Non-ferrous metal sorting device equipped with a rotating drum with magnets.