JPH0985120A - Separation treatment using centrifugal separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate solid substances by a centrifugal separator using the difference of specific gravities without causing the contamination of recovered substance and medium liquid. SOLUTION: In this method for separating the solid substances different from each other in specific gravity by the centrifugal separator 1 by using the medium liquid, a flocculant and/or adsorbent are added 22 to the medium liquid and contaminants in the medium liquid C is flocculated and/or adsorbed and a particle group B having larger specific gravity than that of the medium liquid C is formed and is discharged to a heavy weight substance side 10, thus a purified medium liquid C and a recovered substance A are obtained. from 9, 11. The flocculant and/or the adsorbent 22 into the medium liquid is preferably added in an agitation mixing tank 13 for mixing solid substance of a raw material with a medium liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and treating by a centrifuge, and in particular, a method for separating a solid mixed substance group such as waste plastic by utilizing a difference in specific gravity between a medium and a centrifuge. It is about.

[0002]

2. Description of the Related Art Conventionally, there is a method of separating a plastic, which is lighter than a liquid, from a solid mixed substance group such as a mixed waste plastic using a centrifuge by utilizing a difference in specific gravity from a medium liquid, with extremely high accuracy. In the above-mentioned method, for example, when water is used as a medium liquid and plastic is recovered from the separated collection waste crushed to an appropriate size as a raw material, polyethylene having a specific gravity of 0.91 to 0.86 which is lighter than water having a specific gravity of 1 or specific gravity So-called polyolefins such as polypropylene with 0.90 to 0.91 float on the water surface as a lightweight substance and have a specific gravity of 1
Heavier vinyl chloride, polyamide and most other plastics, and heavy substances such as paper, cloth, metal and earth and sand are almost completely excluded as foreign substances.

Therefore, it is possible to sort the light weight substance with extremely high sorting accuracy and recovery rate as compared with the cyclone system and the like.
Furthermore, due to the stirring effect during centrifugation, recovered substances (lightweight substances)
Foreign matter such as paper adhering to is peeled and removed. Since it is dehydrated by the effect of centrifugal force, the water content of the recovered substance is low. Foreign matter that is heavier than water will migrate to the side of heavy substances if it is insoluble in water, so it has relatively excellent features such as relatively little water contamination. However, in this method, when targeting municipal solid wastes containing a large amount of light-density pollutants such as water-soluble pollutants and oils and fats, the weak point of this method is that not only the water treatment load increases but also the specific gravity There is a problem that substances such as fats and oils that are lighter than 1 migrate to the lightweight substance (recovered substance) side and contaminate the recovered substance.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a separation treatment method by a centrifuge using a difference in specific gravity that does not contaminate recovered substances and medium liquids. To do.

[0005]

In order to solve the above problems, in the present invention, a solid substance having a different specific gravity is separated by a centrifuge in a treatment method using a medium liquid. And / or an adsorbent is added to cause the pollutants in the medium liquid to aggregate and / or adsorb to form a group of particles having a larger specific gravity than the medium liquid, and to remove this toward the heavy substance side to purify the medium liquid and This is to obtain the recovered substance. In the above-mentioned treatment method, the addition of the coagulant and / or the adsorbent to the medium liquid is preferably carried out in a stirring and mixing tank in which the solid material as the raw material and the medium liquid are mixed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The coagulant and / or adsorbent added in the present invention has an adsorbing action as well as strengthening coagulation, and has an effect of increasing the specific gravity of flocs, for example, bentonite and effective for adsorbing and removing fats and oils, For example, activated carbon, zinc hydroxide polymer flocculants (cations, anions, nonions), sulphate buds, PAC, iron salts such as ferric chloride, or the like, or a mixture thereof may be used. Further, it is desirable to use a hard substance that has low tackiness and that facilitates separation of contaminants by the impact of contact with the recovered substance. The solid substance to which the present invention is applicable is, for example, plastic-containing waste (urban waste, industrial waste), etc.
Water, saline, and various salt aqueous solutions can be used.

According to the present invention, the coagulant and / or
Or, because an adsorbent is added, the flocs that have aggregated and adsorbed fine suspended solids and water-soluble pollutants in the medium liquid (water) are automatically removed to the heavy substance side by the centrifugal force effect originally possessed by this method. Not only the medium liquid (water) is purified, but also oils and fats with a specific gravity of less than 1 are separated from the light weight substance (recovered substance) by the agitation action during centrifugation and contact impact with the coagulation / adsorbent. At the same time, since it is adsorbed and removed to the side of the heavy substance, there is a double advantage that the recovered substance is also purified.

The present invention will be specifically described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of an apparatus for carrying out the separation treatment method of the present invention. In FIG. 1, a centrifuge 1
Is composed of a rotary cylinder 3 having two cones 2 and 2 ', and a rotary shaft 4 which rotates at a speed slightly different from that of the rotary cylinder. Two rotary shafts 4 convey two left and right screw conveyors 5, respectively. 6, a partition disk 7, a raw material supply hole 8 are provided, and a light weight substance discharge port 9, a heavy substance discharge port 10, and a medium liquid discharge pipe 11 are provided in the rotary cylinder. In the figure, A indicates a lightweight substance, B indicates a heavy substance, and C indicates a medium liquid. Further, the rotating body 3 is covered with a case 12, and the case has outlets 9'for the respective substances A, B and C,
10 'and 11' are provided.

The medium liquid is stirred and mixed by the stirring blade 15 together with the raw material D supplied from the raw material charging port 14 of the stirring and mixing tank 13, and is passed through the raw material supply hole 8 by the circulation pump 16 into the rotary drum 3. Is supplied to. The liquid surface of the medium is always kept at the water surface 21 determined by the position inside 20 of the discharge pipe 11 by the centrifugal force generated by the rotation of the rotary drum 3. In the figure, 17 is a medium liquid that is replenished from the outside of the system as needed, 18 is a valve for extracting heavy foreign matter in the raw material D precipitated in the bottom of the tank, and 19 is a drive motor for the stirring blade. The above apparatus configuration is conventionally known, and in the present invention, the medium liquid (water) is added to the medium liquid circulation system (preferably in the existing stirring and mixing tank 13) by the flocculation / adsorbent addition device 22. The coagulant and / or the adsorbent is supplied while controlling the supply amount according to the degree of contamination.

[0010]

According to the present invention, the pollutants in the medium liquid are aggregated and / or adsorbed to form a group of particles having a larger specific gravity than the medium liquid, and the particles are eliminated to the side of the heavy substance, whereby the medium liquid is removed. Also, since it is possible to purify lightweight substances, that is, recovered substances, the centrifugal separation method can be easily adopted even in the case of municipal solid wastes containing a large amount of water-soluble pollutants and light specific gravity pollutants such as fats and oils. .

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for carrying out a separation processing method of the present invention.

[Explanation of symbols]

1: Centrifuge 2, 2 ': Cone, 3: Rotating cylinder, 4: Rotating shaft, 5, 6: Screw conveyor, 7: Partition disk,
8: Raw material supply hole, 9, 9 ': Light weight material discharge port, 10, 1
0 ': heavy substance discharge port, 11, 11': medium liquid discharge pipe,
12: case, 13: stirring and mixing tank, 14: raw material inlet,
15: stirring blade, 16: circulation pump, 17: medium liquid replenishing port, 18: heavy foreign matter extraction valve, 19: drive motor,
20: Medium liquid outlet, 21: Water surface, 22: Coagulation / adsorbent addition device. A: Lightweight substance, B: Heavy substance, C: Medium liquid

Claims (2)

[Claims] 1. A method of separating solid substances having different specific gravities by a centrifuge using a medium liquid, wherein a flocculant and / or an adsorbent is added to the medium liquid to condense contaminants in the medium liquid. And / or adsorbing it to form a group of particles having a larger specific gravity than the medium liquid, and removing this to the side of the heavy substance to obtain a purified medium liquid and a recovered substance. . 2. The centrifuge according to claim 1, wherein the coagulant and / or the adsorbent is added to the medium liquid in a stirring and mixing tank for mixing the solid substance as a raw material and the medium liquid. Sorting method by.