JP7142438B2 - Specific gravity sorting device and specific gravity sorting method - Google Patents

Description

The present invention relates to, for example, a gravity sorting apparatus and a gravity sorting method for sorting objects immersed in liquid.

Conventionally, the plastics used in used home appliances are collected and recycled. Collected plastics contain several different types of plastics. The collected plastics are pulverized and sorted by type to become new plastic materials. A mixture of a plurality of different types of crushed plastics is hereinafter referred to as a plastic mixture.

Plastic mixtures mainly contain polypropylene (PP), polystyrene (PS) and acrylonitrile-butadiene-styrene (ABS). Plastic mixtures also include polycarbonate (PC), vinyl chloride (PVC) used in wire coating materials, and the like. The specific gravity of each plastic is about 0.9 for PP, about 1.05 for PS and ABS, 1.2 for PC, and about 1.4 for PVC. A wet-type specific gravity sorter utilizes this difference in specific gravity to sort plastic mixtures by separating and stacking plastics according to their specific gravities in a liquid.

However, if the precision of separation and lamination is low, different plastics will be mixed with each other and the purity of the plastics in each layer will be lowered. Then, physical properties such as strength and elongation of the sorted plastic change. Therefore, the sorting machine is required to have high sorting accuracy. Therefore, a wet-type specific gravity sorter is disclosed that improves the sorting accuracy of each plastic by supplying a plastic mixture in a liquid, pulsating the liquid up and down, and moving each plastic up and down (for example, Patent Document 1 reference).

When the liquid is vertically pulsated, the vertical movement distance of each plastic is long for plastics with low specific gravity and short for plastics with high specific gravity. The specific gravity sorter of Patent Document 1 utilizes this characteristic to give each plastic in the liquid a fluidization start speed and to make the pulsation waveform variable, thereby improving the sorting accuracy of each plastic.

Japanese Patent Application Laid-Open No. 2006-320881

However, Patent Document 1 has the following problems. The collected plastic mixture contains foreign matter such as metal that could not be separated in the previous process. These contaminants accumulate in the sorting tank liquid over time. Then, even if the liquid in the sorting tank is pulsated up and down, the accumulated foreign matter acts as a barrier, and the pulsating flow velocity becomes uneven in the sorting tank. If the flow velocity of the pulsation is non-uniform, even plastics with the same specific gravity will move up and down at different distances. That is, the moving distance of the plastic is long in a place where the flow velocity is high, and the distance that the plastic moves is short in a place where the flow velocity is slow. As a result, plastics with high specific gravity, which have moved up and down for a long distance in places where the flow velocity is high, accumulate on the surrounding plastics with low specific gravity, resulting in reduced sorting accuracy. This problem cannot be solved even if the pulsation waveform is changed.

The present invention has been made to solve the above problems, and even if foreign matter is accumulated in the sorting tank, the object to be sorted can be sorted with high accuracy. An apparatus and a gravity sorting method are obtained.

A specific gravity sorting apparatus according to the present invention includes a sorting tank, a liquid arranged in the sorting tank in which objects to be sorted are immersed, a pulsation generating mechanism for pulsating the liquid, and a movement limiting mechanism, The mechanism is at least partially disposed within the liquid to limit the range of vertical movement of the items to be sorted within the liquid.

The specific gravity sorting apparatus of the present invention separates the plastic mixture into plastics with different specific gravities with high accuracy by limiting the range in which the plastic mixture in the sorting tank can move up and down in the sorting tank. can be laminated with high purity in order of size. This makes it possible to improve the sorting accuracy of the plastic mixture.

1 is a schematic diagram showing a gravity sorter according to Embodiment 1 of the present invention; FIG. FIG. 2 is a schematic diagram showing a state in which the liquid is pulsated in the gravity sorter of FIG. 1; FIG. 2 is a schematic diagram showing a state without a movement restricting mechanism in the gravity sorting apparatus of FIG. 1; FIG. 4 is a schematic diagram showing a modification of the gravity sorter according to Embodiment 1 of the present invention; FIG. 4 is a schematic diagram showing a gravity sorter according to Embodiment 2 of the present invention. FIG. 3 is a schematic diagram showing a gravity sorter according to Embodiment 3 of the present invention. FIG. 4 is a schematic diagram showing a gravity sorter according to Embodiment 4 of the present invention.

Preferred embodiments of the gravity sorting apparatus of the present invention will be described below with reference to the drawings. In addition, in each embodiment, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted. Also, each drawing is schematic, and the dimensions of each part and the ratio of each part to each other may differ from the actual ones.

Embodiment 1.
FIG. 1 is a schematic diagram showing a gravity sorter 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the specific gravity sorting device 1 has a tank 2, a sorting tank 4, a liquid 5, a screen 8, a pulsation generating mechanism 9, a movement limiting mechanism 10, and a circulation pump 13. there is

A tank 2 stores a plastic mixture to be sorted. The plastic mixture contains a light plastic 6 with a small specific gravity and a heavy plastic 7 with a large specific gravity. The plastic mixture also contains foreign matter 14 such as metal that was not separated and collected in the previous step.

Tank 2 has supply port 3 . The tank 2 supplies the plastic mixture to the sorting tank 4 of the gravity sorter 1 through the supply port 3 . The plastic mixture supplied from the supply port 3 also contains a plurality of foreign substances 14 such as metal.

A sorting tank 4 stores a liquid 5 . An example of the liquid 5 is water with a specific gravity of 1.0. Note that the liquid 5 is not limited to water. The sorting tank 4 also has a screen 8 . Screen 8 is immersed in liquid 5 stored in sorting tank 4 .

The screen 8 is shaped to allow the passage of the liquid 5 but not the plastic mixture. The screen 8 then retains the plastic mixture supplied from the tank 2 on its surface. The screen 8 is made of, for example, punching metal, net, or mesh cloth. The material and shape of the screen 8 may be of any type as long as the liquid 5 can pass through it and the plastic mixture does not pass through it.

The sorting tank 4 has a first discharge section 11 for discharging light plastics 6 and a second discharge section 12 for discharging heavy plastics 7 . The first discharge part 11 is arranged above the sorting tank 4 and discharges the light plastics 6 to the outside of the sorting tank 4 together with the liquid 5 above. The second discharge part 12 is arranged below the sorting tank 4 and discharges the heavy plastics 7 to the outside of the sorting tank 4 together with the liquid 5 below. The discharged liquid 5 is collected and returned to the sorting tank 4 by the circulation pump 13 .

Furthermore, the sorting tank 4 has a pulsation generating mechanism 9 below the screen 8 . The pulsation generating mechanism 9 has a mechanism for vertically pulsating the liquid 5 stored in the sorting tank 4 . The configuration of the pulsation generating mechanism 9 is the same as that of the conventional pulsation generating mechanism, and the description thereof is omitted here.

The movement restriction mechanism 10 is fixed in the sorting tank 4 with at least its bottom surface immersed in the liquid 5 . Between the bottom 10b of the movement limiting mechanism 10 and the screen 8, the supplied plastic mixture accumulates. The accumulated plastic mixture moves up and down due to the pulsation of the liquid 5, and along with the flow of the liquid 5 by the circulation pump 13, moves from the supply side to the discharge side. The movement-limiting mechanism 10 is designed so that the distance c from the top of the accumulated plastic mixture to the bottom 10b of the movement-limiting mechanism 10 is equal to the average thickness of the plastic mixture accumulated at the bottom of the movement-limiting mechanism 10. It is placed at a position smaller than t.

The thickness t of the deposited plastic mixture is determined by the flow rate of the liquid 5 from the supply side to the discharge side, which is set by the circulation pump 13 . Therefore, the distance c from the upper portion of the accumulated plastic mixture to the bottom portion 10b of the movement limiting mechanism 10 is set according to the accumulation state of the plastic mixture. The deposited thickness t of the plastic mixture may be obtained by averaging the values obtained by measuring the height of the upper surface of the plastic mixture at several points using a measuring instrument such as a laser displacement meter.

By arranging the movement limiting mechanism 10 at such a position, the upward movement range of the plastic mixture is limited to a range smaller than the accumulated thickness t of the plastic mixture. As a result, the light plastic 6, which travels a long distance during pulsation, collides with the bottom portion 10b of the movement limiting mechanism 10 when rising, and cannot rise any further, and stays below the movement limiting mechanism 10. FIG. On the other hand, the heavy plastic 7, which travels a short distance during pulsation, is limited in the range in which it rises due to the light plastic 6 that stays above.

In the vicinity of the gaps between the plurality of foreign substances 14, the flow velocity of the liquid 5 increases during pulsation, so the moving distance of the heavy plastic 7 increases. Even in such a case, the movement limiting mechanism 10 forms a barrier of the light plastics 6 below the movement limiting mechanism 10, so the lifting range of the heavy plastics 7 is limited.

As described above, the gravity sorter 1 of Embodiment 1 has the movement limiting mechanism 10 that limits the vertical movement range of the plastic mixture. The movement restricting mechanism 10 is arranged at a position such that the distance c from the top of the accumulated plastic mixture to the bottom 10b of the movement restricting mechanism 10 is smaller than the thickness t of the accumulated plastic mixture. When the liquid 5 is pulsated, the specific gravity sorter 1 forms a barrier of the light plastic 6 under the movement restricting mechanism 10 to restrict the upward movement of the heavy plastic 7 . As a result, the gravity sorter 1 prevents the heavy plastics 7 from moving above the light plastics 6 and prevents the light plastics 6 and the heavy plastics 7 from being mixed with each other. As a result, the light plastics 6 and the heavy plastics 7 are separated by specific gravity with high precision in the sorting tank 4 and stacked in order of specific gravity with high precision. Therefore, according to the specific gravity sorting device 1 of Embodiment 1, it is possible to sort out the light plastics 6 and the heavy plastics 7 with high accuracy.

Next, the operation of the gravity sorter 1 according to Embodiment 1 of the present invention will be described.

As shown in FIG. 1, in the plastic mixture supplied from the tank 2 to the sorting tank 4 through the supply port 3, the closer the position to the supply port 3, the more the light plastics 6 and the heavy plastics 7 are mixed. When the pulsation generating mechanism 9 is operated to pulsate the liquid 5 up and down, the plastic mixture pulsates up and down as shown in FIG. Due to this pulsation, the light plastic 6 contained in the plastic mixture moves above the liquid 5 and the heavy plastic 7 moves below the liquid 5 .

A plurality of foreign substances 14 are unevenly distributed and deposited on the surface of the screen 8 . Above the location where the foreign matter 14 is deposited, the flow velocity of the liquid 5 becomes slow during pulsation. On the other hand, the flow velocity of the liquid 5 increases above the location where the foreign matter 14 is not deposited. Furthermore, as in part A of FIG. 2, in a place where a plurality of foreign substances 14 are closely deposited, the flow velocity of the liquid 5 passing between the adjacent foreign substances 14 locally increases. The heavy plastics 7 positioned around the A portion may move upwards from the surrounding light plastics 6 and accumulate on top of the surrounding light plastics 6 . Then, the light plastic 6 and the heavy plastic 7 are mixed, and there is a possibility that they are not laminated according to their specific gravities.

However, in the specific gravity sorter 1 of Embodiment 1, the upward movement range of the plastic mixture is restricted by the movement restriction mechanism 10 . As a result, the light plastic 6 with a long movement distance collides with the bottom portion 10b of the movement limiting mechanism 10. As shown in FIG. The light plastic 6 then remains below the movement limiting mechanism 10 to form a barrier. Then, the heavy plastic 7 cannot move above the light plastic 6 due to the barrier of the light plastic 6 . Therefore, the lamination of the light plastic 6 and the heavy plastic 7 is maintained for each specific gravity.

As the pulsation of the liquid 5 continues, the heavy plastic 7 with a short moving distance accumulates below, and the light plastic 6 with a large moving distance is stacked on top of the heavy plastic 7 . Then, the light plastics 6 positioned above are discharged from the first discharge portion 11 to the outside of the sorting tank 4 together with the liquid 5 . On the other hand, the heavy plastics 7 positioned below are discharged from the second discharge portion 12 to the outside of the sorting tank 4 together with the liquid 5 .

Along with this, the plastic mixture in the sorting tank 4 moves from the supply side to the discharge side while being stacked according to specific gravity. The light plastics 6 and the heavy plastics 7 discharged to the outside of the sorting tank 4 are separated from the liquid 5 and recovered. The liquid 5 is returned to the sorting tank 4 by the circulation pump 13 .

Here, the behavior of the plastic mixture when the gravity sorter 1 does not have the movement limiting mechanism 10 will be described with reference to FIG. FIG. 3 shows the state in which the liquid 5 is pulsated. In a place where a plurality of foreign substances 14 are deposited close to each other, as in part B of FIG. 3, the flow velocity of the liquid 5 passing between adjacent foreign substances 14 is locally increased. Then, the heavy plastic 7 positioned around the B portion moves above the surrounding light plastic 6 and deposits on the surrounding light plastic 6 . Then, the light plastic 6 and the heavy plastic 7 are mixed, and the lamination of the light plastic 6 and the heavy plastic 7 is disturbed, so that highly accurate sorting cannot be performed.

As described above, the gravity sorter 1 of Embodiment 1 has the movement limiting mechanism 10 that limits the upward movement range of the plastic mixture in the sorting tank 4 . As a result, even if the flow velocity of the liquid 5 in the sorting tank 4 becomes uneven due to the presence of the foreign matter 14, the light plastics 6 and the heavy plastics 7 can be separated with high accuracy, and the plastics are separated in order of specific gravity. It can be laminated with high precision. Therefore, the light plastics 6 and the heavy plastics 7 can be sorted out with high precision and recovered with high purity.

In addition, in Embodiment 1, the movement restriction mechanism 10 has been described as being fixed, but the movement restriction mechanism 10 may be movable. For example, the specific gravity of the movement restricting mechanism 10 may be made smaller than the specific gravity of the liquid 5 so that the movement restricting mechanism 10 floats on the liquid 5 .

Further, as shown in FIG. 4, for example, the movement limiting mechanism 10 may be supported by a motor 21 and a support member 22 attached to the motor 21 so as to be vertically movable. Then, when the deposited thickness t of the plastic mixture fluctuates, the movement limiting mechanism 10 may be raised and lowered according to the fluctuation of the thickness t. As a result, even when the amount of the plastic mixture supplied to the sorting tank 4 fluctuates and the thickness t of the plastic mixture deposited on the screen 8 fluctuates, the position of the movement limiting mechanism 10 can be moved and the distance c can be maintained at a suitable value.

Embodiment 2.
FIG. 5 is a schematic diagram showing a gravity sorter 1A according to Embodiment 2 of the present invention. A specific gravity sorting apparatus 1A of the second embodiment differs from the movement limiting mechanism 10 of the first embodiment in the configuration of the movement limiting mechanism 15 . Other configurations are the same as those of the first embodiment.

The movement restricting mechanism 15 of the second embodiment has a through hole 16 which has an inner diameter through which the liquid 5 can pass and through which the light plastic 6 and the heavy plastic 7 to be sorted cannot pass. have one or more. The horizontal cross-section of the through-hole 16 may be circular, polygonal, or any other shape.

According to the specific gravity sorting apparatus 1A of Embodiment 2 formed in this way, when the liquid 5 is pulsated up and down by the pulsation generating mechanism 9, the liquid 5 can pass through the through hole 16 of the movement limiting mechanism 15. I have to. As a result, it is possible to suppress the occurrence of turbulence in the liquid 5 due to the liquid 5 pulsating and colliding with the bottom surface 15 b of the movement restricting mechanism 15 . Therefore, it is possible to suppress disturbance of the lamination of the light plastic 6 and the heavy plastic 7 due to turbulent flow in the liquid 5 .

Embodiment 3.
FIG. 6 is a schematic diagram showing a gravity sorter 1B according to Embodiment 3 of the present invention. A specific gravity sorting device 1B of the third embodiment differs from the movement limiting mechanism 10 of the first embodiment in the configuration of a movement limiting mechanism 17. FIG. Other configurations are the same as those of the first embodiment.

The movement restricting mechanism 17 of Embodiment 3 is formed by a plurality of movement restricting members 17a, and each movement restricting member 17a is horizontally connected by a connecting member 18. As shown in FIG. The shape of each movement restricting member may be a sphere, a cylinder, a rectangular parallelepiped, or a combination thereof.

Each space between the adjacent movement restricting members 17a is set to a space through which the liquid 5 can pass but through which the light plastics 6 and the heavy plastics 7 to be sorted cannot pass.

According to the specific gravity sorter 1B of Embodiment 3 formed in this way, when the liquid 5 is pulsated up and down by the pulsation generating mechanism 9, the liquid 5 passes between the respective movement restricting members. As a result, it is possible to suppress the occurrence of turbulent flow of the liquid 5 due to the pulsation of the liquid 5 colliding with the bottom surface 17b of each movement restricting member 17a. Therefore, the stacking of the light plastics 6 and the heavy plastics 7 is not disturbed by the turbulent flow of the liquid 5, and sorting can be performed with higher accuracy.

Embodiment 4.
FIG. 7 is a schematic diagram showing a gravity sorter 1C according to Embodiment 4 of the present invention. A specific gravity sorter 1C according to the fourth embodiment differs from the movement limiting mechanism 10 according to the first embodiment in the configuration of the movement limiting mechanism 19 . Other configurations are the same as those of the first embodiment.

The movement restricting mechanism 19 of Embodiment 4 is formed by a plurality of movement restricting members 19a, and around the plurality of movement restricting members 19a is a restricting member 20 for restricting the horizontal movement range of each movement restricting member 19a. surrounded by The shape of each movement restricting member 19a may be a sphere, a cylinder, a rectangular parallelepiped, or a combination thereof.

The restricting member 20 has a plurality of movement restricting members 19a so that even if the distance between the adjacent movement restricting members 19a widens to the maximum, the distance does not exceed the distance through which the light plastics 6 and the heavy plastics 7 to be sorted can pass. 19a.

According to the specific gravity sorter 1 of Embodiment 4 formed in this way, when the liquid 5 is pulsated vertically by the pulsation generating mechanism 9, the liquid 5 passes between the movement restricting members 19a. As a result, it is possible to suppress the occurrence of turbulence in the liquid 5 due to the liquid 5 pulsating and colliding with the bottom surface 19 b of the movement restricting mechanism 19 . Therefore, the stacking of the light plastics 6 and the heavy plastics 7 is not disturbed by the turbulent flow of the liquid 5, and sorting can be performed with higher accuracy.

In the first to fourth embodiments, the material to be sorted is a plastic mixture, and the light plastic 6 and the heavy plastic 7 are sorted according to their specific gravities. However, the material to be sorted is not limited to a plastic mixture. . For example, if it is a mixture of a plurality of different substances that have a higher specific gravity than the liquid 5 and can move up and down in the liquid 5 according to the pulsation of the liquid 5, the gravity sorting devices of Embodiments 1 to 4 are used. It is possible to sort by specific gravity.

1, 1A, 1B, 1C Gravity sorting device, 2 tank, 3 supply port, 4 sorting tank, 5 liquid, 6 light plastic, 7 heavy plastic, 8 screen, 9 pulsation generation mechanism, 10, 15, 17, 19 movement restriction Mechanism 11 First Discharge Part 12 Second Discharge Part 13 Circulation Pump 14 Foreign Matter 16 Through Hole 17a, 19a Movement Limiting Member 18 Connecting Member 20 Regulating Member 21 Motor 22 Supporting Member.

Claims (8)

a sorting tank;
a liquid placed inside the sorting tank, in which the objects to be sorted, which are plastic mixtures, are immersed;
A specific gravity sorting device that includes a pulsation generating mechanism that pulsates the liquid to move the objects to be sorted up and down, and separates and sorts the objects to be sorted by specific gravity,
having a movement restriction mechanism,
The sorting tank has a screen immersed in the liquid,
The liquid is a liquid on which the objects to be sorted are deposited,
a bottom portion of the movement restriction mechanism is immersed in the liquid;
When the material to be sorted supplied between the bottom and the screen is deposited, the distance from the top of the deposited material to be sorted to the bottom is a non-zero positive value,
The deposited objects to be sorted move up and down due to the pulsation of the liquid,
The movement limiting mechanism limits a vertical movement range of the object to be sorted in the liquid,
The specific gravity sorting device, wherein the movement restricting mechanism is supported by an elevating device so as to be vertically movable. a sorting tank;
a liquid placed inside the sorting tank, in which the objects to be sorted, which are plastic mixtures, are immersed;
A specific gravity sorting device that includes a pulsation generating mechanism that pulsates the liquid to move the objects to be sorted up and down, and separates and sorts the objects to be sorted by specific gravity,
having a movement restriction mechanism,
The sorting tank has a screen immersed in the liquid,
The liquid is a liquid on which the objects to be sorted are deposited,
a bottom portion of the movement restriction mechanism is immersed in the liquid;
When the material to be sorted supplied between the bottom and the screen is deposited, the distance from the top of the deposited material to be sorted to the bottom is a non-zero positive value,
The deposited objects to be sorted move up and down due to the pulsation of the liquid,
The movement limiting mechanism limits a vertical movement range of the object to be sorted in the liquid,
the specific gravity of the movement restricting mechanism is smaller than the specific gravity of the liquid;
The gravity sorting device, wherein the movement restriction mechanism is suspended in the liquid. The movement restriction mechanism has at least one through-hole penetrating in the vertical direction,
The through-hole has an inner diameter through which the liquid can pass and which is smaller than the outer diameter of the object to be sorted,
The specific gravity sorter according to claim 1 or 2. The movement-limiting mechanism is formed by a plurality of movement-limiting members that are horizontally spaced apart from each other and connected,
Each of the intervals is set so that the liquid can pass through and is smaller than the outer diameter of the object to be sorted,
The specific gravity sorter according to claim 1 or 2. The movement restriction mechanism is formed by a plurality of movement restriction members arranged independently of each other in the horizontal direction,
the periphery of the plurality of movement restricting members is surrounded by a restricting member that restricts a horizontal movement range of each of the movement restricting members;
The restricting member restricts each distance between the adjacent movement restricting members to a distance smaller than the outer diameter of the object to be sorted.
The specific gravity sorter according to claim 1 or 2. The movement restriction mechanism is
The distance from the top of the object to be sorted deposited in the sorting tank to the bottom surface of the movement limiting mechanism is arranged at a position smaller than the thickness of the deposited object to be sorted,
The specific gravity sorter according to claim 1 or 2. the liquid is water;
The specific gravity of the material to be sorted is greater than 1.0,
The gravity sorter according to any one of claims 1 to 6. A gravity sorting method for sorting objects to be sorted using the gravity sorting device according to any one of claims 1 to 7,
a step of supplying the objects to be sorted into the sorting tank in which the liquid is placed;
a step of immersing the objects to be sorted in the liquid;
pulsating the liquid up and down by the pulsation generating mechanism;
a step of vertically moving the objects to be sorted in the liquid by the pulsation;
a step of limiting the range of vertical movement of the objects to be sorted by the movement limiting mechanism;
A step of stacking the objects to be sorted in order of specific gravity;
a step of discharging the objects to be sorted according to specific gravity;
Gravity sorting method.

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