JPH05146705A - Method for sorting crushed plastic by specific gravity and apparatus therefor - Google Patents

Abstract

PURPOSE:To provide a method and apparatus for accurately sorting a crushed plastic mixture of polypropylene, polystyrene, polyvinyl chloride, etc., by specific gravity. CONSTITUTION:Compressed air 32 is fed to an air diffuser plate 20 installed in the bottom part of a water tank 10 and fine bubbles formed by the air diffuser plate 20 are quantitatively blown in water stored in a water tank 10 to uniformly mix them with water, causing apparent gravity of water to be <=1.0. Thereby crushed plastic of <=1.0 specific gravity is sorted with good accuracy and by specific gravity from the mixture of two or more kinds of crushed plastic including granules of <=1.0 specific gravity and differing in specific gravity. Since specific gravity liquid 34 prepared by the operation is water, when it is used combined with other specific gravity liquid, such as water solution of inorganic salt, there is no problem on change in set specific gravity and pollution due to a mutual mixing of specific gravity liquids.

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 separating mixed crushed plastics, and more particularly to a method and an apparatus for separating specific gravity of mixed plastics such as polypropylene, polystyrene and vinyl chloride.

[0002]

2. Description of the Related Art Conventionally, for classification of mixed plastics, a method of separating crushed plastics by wind force based on the difference between its own weight and air resistance, and a method of separating crushed materials in water or various specific gravity liquids by utilizing the difference in specific gravity , A flotation method that separates the water based on how the bubbles are formed by rough water and surface modification.

Among the above methods, the specific gravity fractionation method is not easily affected by the shape and size, and is therefore advantageous for the fractionation of plastics which are difficult to grind into a uniform particle size.

[0004]

However, an aqueous solution in which an inorganic salt is dissolved in water is often used as a specific gravity liquid for specific gravity separation. An aqueous solution of an inorganic salt produces a specific gravity liquid having a specific gravity of 1.0 or more. Even if it is easy, it is impossible to make a specific gravity liquid having a specific gravity of 1.0 or less. Therefore, it has been difficult to accurately separate the crushed plastic having a specific gravity of 1.0 or less from a mixture of two or more kinds of crushed plastic having different specific gravities, which contains the crushed plastic having a specific gravity of 1.0 or less.

As a solution to this problem, it is conceivable to use alcohols or oils in a specific gravity liquid having a specific gravity of 1.0 or less, but it is used in combination with another specific gravity liquid such as an aqueous solution in which an inorganic salt is dissolved. In such a case, a change in the set specific gravity or contamination due to mixing of specific gravity liquids having different characteristics becomes a problem. The present invention is
In view of the above circumstances, it is an object of the present invention to provide a method and a device for separating crushed plastics, which eliminates the drawbacks of the conventional method and accurately separates the crushed plastics mixed with polypropylene, polystyrene, vinyl chloride, etc. with specific gravity. With the goal.

[0006]

In order to achieve the above object, the present invention separates a mixture of two or more kinds of crushed plastics having different specific gravities and containing crushed plastics having a specific gravity of 1.0 or less by type. In the method for fractionating specific gravity of crushed plastic, fine air bubbles of high-pressure air are quantitatively and uniformly mixed with water, and a specific gravity liquid having a specific gravity of 1.0 or less is prepared by the above-mentioned mixing operation. A specific gravity liquid having a specific gravity of 0.0 or less is charged with a mixture of two or more types of crushed plastics having a specific gravity of 1.0 or less and having different specific gravities, and a crushed plastic having a specific gravity smaller than the preset specific gravity is added. It is characterized in that it is floated on the specific gravity liquid, and crushed plastic having a specific gravity larger than the set specific gravity is allowed to settle on the specific gravity liquid for separation.

In order to achieve the above object, the present invention is an apparatus for separating the specific gravity of crushed plastics, which classifies a mixture of two or more kinds of crushed plastics having different specific gravities and containing crushed plastics having a specific gravity of 1.0 or less. , A water tank that stores water and separates the mixture of crushed plastics into those that float and those that settle due to the difference in specific gravity; a supply means that supplies the mixture of crushed plastics to the water tank; and a high pressure to the water in the water tank. And an air diffuser for quantitatively blowing fine air bubbles.

[0008]

As described below, the present invention separates crushed plastics having a specific gravity of 1.0 or less from a mixture of two or more kinds of crushed plastics having different specific gravities, which contains crushed plastics having a specific gravity of 1.0 or less. When doing so, first, high-pressure air is sent to the diffuser plate provided in the water tank, and the fine bubbles formed by the diffuser plate are quantitatively blown into the water stored in the water tank to uniformly mix them. To do.

By the above-mentioned operation, the specific gravity of the water stored in the water tank can be apparently 1.0 or less, and the amount of air mixed with the water stored in the water tank can be changed. The apparent specific gravity of water can be adjusted. When a mixture of two or more kinds of crushed plastics having different specific gravities and containing crushed plastics having a specific gravity of 1.0 or less is added to the specific gravity liquid having an apparent specific gravity of 1.0 or less prepared by the above operation, the mixture is charged. In the mixture, the crushed plastic having a specific gravity smaller than the set specific gravity floats on the specific gravity liquid, and the crushed plastic having a specific gravity larger than the set specific gravity settles in the specific gravity liquid.

Thus, the crushed plastic having a specific gravity of 1.0 or less can be accurately separated from the mixture of two or more kinds of crushed plastic having different specific gravities including the crushed plastic having a specific gravity of 1.0 or less. ..

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method and apparatus for separating specific gravity of particles according to the present invention will be described in detail below with reference to the accompanying drawings. As shown in FIG. 1, a light specific gravity liquid tank 10 and a heavy specific gravity liquid tank 12 are provided in parallel, and an upper portion of the light specific gravity liquid tank 10 contains particles having a specific gravity of 1.0 or less, A mixed particle supply tank 14 is provided for storing a mixture of a plurality of particles (crushed plastics) having different specific gravities.

Further, a screw conveyor 16 for transporting and feeding the mixture from the mixed granular material supply tank 14 to the light specific gravity liquid tank 10 is disposed below the mixed granular material supply tank 14 and The outlet 18 is located above the light specific gravity liquid tank 10. Light specific gravity liquid tank 1
At the bottom of 0, high pressure air is formed into fine bubbles,
A diffuser plate 20 for uniformly mixing the fine bubbles with the specific gravity liquid is provided, and a high pressure air pipe 22 extends from the diffuser plate 20 through the bottom plate of the light specific gravity liquid tank 10 to a compressor (not shown). It is connected.

Further, in the light specific gravity liquid tank 10 and the heavy specific gravity liquid tank 12, conveyors 24 and 26 for collecting the particles floating in the specific gravity liquid and a conveyor 28 for collecting the settled particles and conveying them to the next step. , 30 are provided respectively. The operation of the specific gravity fractionation of the crushed plastic particles of polypropylene, polystyrene and vinyl chloride in the apparatus having such a configuration will be described.

First, as a preparation, water is stored in the light specific gravity liquid tank 10, a compressor (not shown) is operated, and high pressure air 32 is quantitatively sent to the diffuser plate 20 through the high pressure air pipe 22 to diffuse the high pressure air 32. The fine bubbles formed by the air plate are blown into water to mix them uniformly to prepare a light specific gravity liquid 34 in which the apparent specific gravity of water is maintained at about 0.95. On the other hand, the heavy specific gravity liquid 36 in which magnesium sulfate is dissolved in water and the specific gravity is adjusted to about 1.1 is stored in the heavy specific gravity liquid tank 12.

Further, the plastic in which polypropylene, polystyrene, and vinyl chloride are mixed is crushed into particles having a size of several mm by a method such as low temperature crushing, and the crushed particles are put in the mixed particle supply tank 14. After the above preparations are completed, the mixed particle supply tank 14
From the above, a mixture of polypropylene having a specific gravity of about 0.9, polystyrene having a specific gravity of about 1.0, and crushed plastic of vinyl chloride having a specific gravity of about 1.3 is charged into the light specific gravity liquid tank 10 by the screw conveyor 16.

Since the specific gravity of the light specific gravity liquid 34 is set to about 0.95, the specific gravity of the injected mixture is 0.
The polypropylene granules of about 9 float on the light specific gravity liquid 34 and are recovered by the recovery conveyor 24. On the other hand, the specific gravity is 1.
A mixture of polystyrene of about 0 and granules of vinyl chloride having a specific gravity of about 1.3 settles in the bottom of the light specific gravity liquid tank 10, is recovered by the recovery conveyor 28, and is conveyed to the heavy specific gravity liquid tank 12 and input.

Since the specific gravity of the specific gravity liquid 36 is set to about 1.1, the specific gravity of the mixture of polystyrene and vinyl chloride particles charged into the specific gravity liquid tank 12 is about 1.0. The polystyrene particles float on the gravity liquid 36 and are recovered by the recovery conveyor 26. On the other hand, specific gravity 1.3
About a certain amount of vinyl chloride granules settle at the bottom of the gravity tank 12 and are collected by the collecting conveyor 30.

In this way, a mixture of polypropylene, polystyrene, and vinyl chloride crushed plastic particles having different specific gravities can be accurately separated by specific gravity. Further, even if the light specific gravity liquid 34 of the light specific gravity liquid tank 10 adheres to the plastic particles and is entrained in the heavy specific gravity liquid tank 12 which is an aqueous solution of magnesium sulfate and mixed into the heavy specific gravity liquid 36, the light specific gravity liquid 34 is Since it is water, it does not affect the specific gravity of the gravity fluid 36 or contaminate the gravity fluid 36.

Although water is used as the light specific gravity liquid in the above embodiments, a small amount of a surfactant or the like may be added to the water in order to increase the hydrophilicity of the plastic. In the above embodiment, the case where the three types of crushed plastics are separated by the specific gravity was described, but the present invention is not limited to this, and the specific gravity liquid tank is 3
It is possible to separate four or more kinds of crushed plastic by installing one.

[0020]

As described above, according to the method and apparatus for crushing plastic specific gravity according to the present invention, high-pressure air is sent to the diffuser plate provided at the bottom of the water tank, and fine bubbles are generated by the diffuser plate. And the fine bubbles are uniformly mixed with the water stored in the water tank so that the specific gravity is apparently 1.
A specific gravity liquid of 0 or less can be prepared.

Thus, the crushed plastic having a specific gravity of 1.0 or less can be accurately separated from the mixture of two or more kinds of crushed plastic having different specific gravities including the crushed plastic having a specific gravity of 1.0 or less. Further, since the specific gravity liquid adjusted in the above operation is water, when used in combination with another specific gravity liquid such as an aqueous solution in which an inorganic salt is dissolved, there is a problem of change in the specific gravity or contamination due to mixing of the specific gravity liquids. I won't.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method and an apparatus for separating specific gravity of crushed plastic according to the present invention.

[Explanation of symbols]

 10 ... Specific gravity liquid tank 20 ... Air diffuser plate 22 ... High pressure air piping 32 ... High pressure air

Claims (2)

[Claims] 1. A method for separating the specific gravity of crushed plastics, in which a mixture of two or more kinds of crushed plastics having different specific gravities, which contains crushed plastics with a specific gravity of 1.0 or less, is classified into fine air bubbles of high pressure air. A specific gravity liquid having a specific gravity of 1.0 or less is prepared by quantitatively and uniformly mixing with water, and the specific gravity of the specific gravity liquid having a specific gravity of 1.0 or less is 1.
A mixture of two or more kinds of crushed plastics having different specific gravities including crushed plastics of 0 or less is introduced, and crushed plastics having a specific gravity smaller than the set specific gravity are floated on the specific gravity liquid, and crushed plastics having a specific gravity larger than the set specific gravity. A method for separating the specific gravity of crushed plastics, characterized by allowing the above-mentioned to settle in the specific gravity liquid for separation. 2. A crushed plastic specific gravity separating apparatus for separating, by type, a mixture of two or more kinds of crushed plastics having different specific gravities, which contains crushed plastics having a specific gravity of 1.0 or less. A water tank that separates the mixture of crushed plastics into one that floats and one that settles due to the difference, a supply means that supplies the mixture of crushed plastics to the water tank, and minute bubbles of high-pressure air are blown into the water in the water tank quantitatively. An apparatus for separating specific gravity of crushed plastics, comprising: an aeration means.