DE4417693C1 - Sorting plastics chips of different densities - Google Patents

Abstract

To sort mixtures of plastics chips, of different densities, the mixture (12) together with a fluid (11) with the chips (1a-1c) is fed into the peak of a conical separation vessel (3) on a horizontal axis (30) with upper and lower (32,33) conical walls. The mixture (12) is moved through the vessel (3) in a laminary flow pattern, giving upwards and downwards movement levels for the chips (1a-1c), so that the lighter chips (1a) are collected at the upper wall (32) and the heavier chips (1b) are collected at the lower wall (33). The separated chip mixtures (13a,13c) are extracted by suction at the end (35) of the vessel (3) near the limit walls (32,33). Also claimed is an appts. with a conical separation vessel (3) on a horizontal axis (30), with the feed (31) at the point on the axis (30). The upper and lower walls (32,33) form an included angle of 15-35 deg.S Suction units (321,331) are at the end (35) of the vessel (3) at the upper and lower walls (32,33).

Description

The invention relates to a method and a Vorrich device for sorting mixtures of plastic cut different densities after the swim-sink Separation process, the plastic chips using Turbulence in a liquid separated and be evenly distributed in the liquid, the plastic chips in a collection container Float or sink depending on their density and in two vertically separated th levels are removed from the separation container.

Methods of the type mentioned above have so far been described in different variants known.

A process has been described by the document DE 29 00 666 C3 ben, in which the plastic particles for the purpose of sorted recovery with the help of so-called Hydrocyclones were separated.

Due to the differentiated mode of action of gravity and centrifugal force become particles of different densities either pushed up or down, total melts and dissipates.

It has been found to be disadvantageous that using this principle only plastics can be sorted nen, which is almost the same and relatively small Have grain size and the same grain mass.

If this is not guaranteed, the Hydrozyk sorts lon not by the density of the plastics, but by the grain size.  

In many cases, this makes the sorting so inaccurate enough that their results are not practically usable are.

Among other things through the publication WO 91/04100 A1 it was proposed that the plastics be replaced by the so-called separate swim-sink process.

The plastic particles of different plastic species are in a liquid in one Separation container by using stirring elements equally distributed. The first floating Plastic particles increase depending on their own density and the density of the liquid either to the surface or they sink to the bottom of the Container.

The suspended particles become on the surface an overflow from which this plastic part be promoted for further processing.

The art sinking due to its higher density Material particles are removed on a conveyor belt on Bottom of the separation container is gripped and over an oblique Level up out of the separation container.

Such a way of working is disadvantageous because on the one hand the stirring movement by the propeller and on the other hand the transport movement of the conveyor belt turbulence generate in the liquid used for the separation process after the swim-sink process are disadvantageous.

The last mentioned shortcoming was tried among other things rem remedy according to the publication DE 41 30 645 A1 in that one after stirring the mixture of liquid and plastic particles through this liquid mixture Interrupting the stirring process came to rest.  

In this resting phase, this should be in the separation container differentiated floating or sinking of the Plastic particles are made.

However, it has been shown that for one if possible perfect separation of the plastic particles certain concentration of these particles in the Separation container must not be exceeded. The sinking and rising plastic particles hindered each other.

A reasonable separation quality was only found at rela tiv low concentration of plastic particles in the liquid reached.

Taking this fact into account, then pro Working interval quali only small amounts of plastic be separated appropriately.

With today's quantities of plastics under of such a variety would work in such a way Enormous size plants may be necessary to the varieties fair recycling of plastics chen.

The further development of the device described through the teaching of DE 42 09 277 A1 defi problem to be solved.

EP 05 57 816 A2 also describes a method and a device for separating plastic mixtures become known, the plastic mixture in the Center one concentrically in the horizontal direction expanding space is introduced.

The flow velocity of the particles decreases from the outside. The flow characteristic is thereby increasingly laminar.

However, this laminar flow area is spacious Lich extremely limited, so that the cylindrical Outer wall the floating and the sinking Interfering with plastic particles. Leading either to constipation or to an unclean one Separation of the different plastics.

The invention has for its object a Ver drive and propose a device for its implementation, in which through a continuous working method the plastic particles depending on the density of the liquid be separated safely and quality-wise and large Plastic quantities sorted with reasonable effort can be.  

This task is achieved through the procedural features of Claim 1 in a surprising manner and in very simple form solved.

Passing the starting mixture and floating on it and sinking plastic particles in one Flow direction, especially in the vertical plane, expanding, completely filled separation container leads to the fact that, after initially sole differences differentiation of the particles according to the density by which conical shape and the flow emerging to the outside Directional suction speeds up the separation without to hinder the sorting process.

The result is a high quality sorting at high throughput at the same time. The concentration of the starting mixture can be significant be chosen higher than with conventional methods. The process can be continuous and requires only a limited amount of manual monitoring.

With the multiple suction of the sorted mixtures Claim 2 is also in a long separation container Optimal separation guaranteed in all areas.

By applying a vibration according to claim 3 better sorting results are achieved.

With the design of the method according to claim 4, can u. U. save additional separation stages.

The device according to claim 5 allows simple technical means the rational realization of the Procedure.  

The design of the device according to claims 6 to 9 ensures optimal use of individual processes reindeer variants.

A mutual handicap on floating and sinking the plastic particle is going through the continuous Movement of the fluid largely restricted. The separation takes place on a larger section of the path and spread over a long time.

The use of a slowly rotating idler Turbulence of the mixing zone shields near the inlet opening ne and promotes the formation of a laminar flow mung.

On the one hand, the vibrator ensures uprightness maintaining the separation of individual plastic parts chen. On the other hand, the necessary laminar flow scarcely adversely affected by the vibrations flows.

The invention is intended to perform some of the following examples are explained in more detail. The related ones Show drawings

Fig. 1 is a schematic illustration of the entire plant for the separation of plastics,

Fig. 2 shows the basic form of the separating tank processes with the identification of the essential method,

Fig. 3 is a representation analogous to FIG. 2, with additional process elements for the distribution of the plastic and the staggered upwards and the removal are indicated by suspended particles, and

Fig. 4, 4a each have a cross-section through the container collecting along the line IV-IV and IVa-IVa in Fig. 2.

The system for separating plastic particles for the recycling of plastics by type is shown in FIG. 1 using the example of a separation system in which plastic particles 1 a, 1 b, 1 c are sorted according to three different densities.

The system works according to the generally known Float-sink process.

The plastic mixture 10 coming from a shredder system is fed to a funnel 21 . It is indicated by an arrow.

At almost the same point, the liquid 11, which is in an almost closed circuit, is fed as possible under high pressure via an inlet pipe 22 in the funnel 21 . (See also Fig. 2) This creates a, usually sufficiently homogeneous mixture of liquid 11 and plastic particles 1 a, 1 b, 1 c, which is referred to below as the starting mixture 12 be.

About a conveniently vertical shaft 23 and a manifold 24 , the starting mixture 12 is introduced through an inlet opening 31 at the top of a conical separation container 3 in the same.

The conical separation container 3 is arranged approximately horizontally with its axis 30 .

It has, as shown in FIG. 4 and FIG. 4a can be seen an approximately rectangular cross section with its lateral surfaces 34 are preferably oriented approximately vertically.

The upper and lower boundary surfaces 32 , 33 form an angle to one another which approximately corresponds in size to the usual outlet area of a Venturi nozzle, namely approximately 15 ° to 35 °.

The upper or lower boundary surface 32 , 33 of the separation container 3 is appropriately curved outwards so that the floating or sunken plastic particles 1 a, 1 c can collect in a very concentrated space.

Very close to the upper or lower boundary surface 32 , 33 , at the end 35 of the separation container 3 , a suction pipe 321 , 331 is connected to each of these boundary surfaces 32 , 33 , through which the floating or sunken plastic particles 1 a, 1 c are suctioned off.

The plastic particles 1 a, 1 c sucked off together with the liquid 11 are fed via a pipeline system to a liquid separator 4 a, 4 c and fed to the transport and further processing by mechanical means ( FIG. 1).

The separated liquid 11 is returned to the process and, if necessary, supplemented by additional liquid.

In the region of the axis of the separation container 3 is, in this embodiment, the separation vessel 3, an additional suction duct 38 arranged at the end 35, which receives the liquid 11 b together with the particles suspended therein. 1 These suspended particles 1 b have approximately the same density as the liquid 11 .

The suspended particles 1 b are collected by a further liquid separator 4 b, which is expediently designed as a filter, and made available for further processing.

If the system with a very high concentration of plastic particles 1 a, 1 b, 1 c in the liquid 11 be operated, it makes sense to consecutively at the upper and / or lower boundary surface 32 , 33 of the separation container 3 in the flow direction of the mixture Suction ports 322 , 323 , 324 ; 332 , 333 , 334 to be arranged ( Fig. 1).

This ensures that over the entire length of the suction container 3 a, the separation of the plastic particles 1 a, 1 b, 1 c supporting suction is maintained.

Relatively large amounts of plastic particles 1 a, 1 b, 1 c can be removed.

When processing large amounts of plastic particles 1 a, 1 b, 1 c and a high concentration of these particles in the liquid 11 , it is necessary that all these particles swim individually and freely in the liquid.

For this purpose, 3 devices of a known type for intensive mixing of liquid 11 and plastic particles 1 a, 1 b, 1 c can be arranged between the funnel 21 and the tip of the separation container.

However, it should be avoided that the Turbulence occurring directly in the mixing process Separation container can be transferred.  

It has proven to be expedient to see a slowly rotating stator 36 with guide vanes for an axial conveying effect at the entrance of the separation container 3 ( FIG. 2).

Such a stator prevents turbulence Isolation container shielded out, and the liquid in a steady steady movement.

The speed of this wheel is with the suction effect of everyone Adjust suction connections, and if necessary, too regulate.

To prevent clumping of plastic particles 1 a, 1 b, 1 c in the separation container 3 , it is advisable to arrange a vibration generator 37 preferably in the tip of the separation container 3 ( FIG. 2).

Such a vibration generator 37 sets the entire liquid 11 in the separation container 3 in vibrations, which prevent plastic particles 1 a, 1 b, 1 c from sticking to one another and sticking to one another through the effect of the surface tension.

This, among other things known from the laundry measure me here leads to the fact that air bubbles that adhere to the plastic parts 1 a, 1 b, 1 c and could affect the sorting process in an unfavorable manner, from the plastic particles 1 a, 1 b , 1 c solved and can be removed upwards.

The air thus released is removed at the top together with the floating plastic particles 1 a on the upper boundary surface 32 of the separation container 3 .

Taking into account that the respective density of the liquid 11 sets the standard for the determination of the respective separation limit, here too one must arrange several of these systems that use liquids with different densities in a row for the separation of very different types of plastic (not shown ).

As can be seen by the person skilled in the art from the previous illustration, it is important in the implementation of this method that the laminar flow of the mixture is obtained in all areas within the separating container 3 as far as possible.

For this reason, one should arrange sensors at various positions, which display different concentrations of plastic particles 1 a, 1 b, 1 c and give appropriate signals to control devices and actuators for the purpose of correction.

By changing the suction power, a variation of the Liquid addition or by regulating the amplitude The vibrations can be corrected to the system realize.

For manual control of the process, one can also select a design of the separation container 3 in such a way that transparent wall surfaces or pipes are provided in critical zones.

Reference list

( 1 ) plastic particles,
1 a plastic particle, floating
1 b plastic particles, floating
1 c plastic particles, sinking

10 plastic waste mixture
11 liquid
12 starting mixture
( 13 ) Mix, sorted
13 a mixture, floating
13 b mixture, pending
13 c mixture, sinking

21 funnels
22 inlet pipe
23 shaft
24 manifolds

3 separation containers
30 axis
31 inlet opening
32 boundary surface, top
321 intake manifold
322 intake manifold
323 intake manifold
324 intake manifold

33 boundary surface, below
322 intake manifold
332 intake manifold
333 intake manifold
334 intake manifold

34 wall, side
35 end
36 idler
37 vibration sensors
38 suction line

4 a liquid separator
4 b liquid separator
4 c liquid separator

Claims (11)

1. A method for sorting mixtures of plastic chips of different density according to the swim-sink separation process, wherein

• the plastic chips are separated from one another by means of turbulence in a liquid and are evenly distributed in the liquid,
• - Float or sink the plastic chips in a separation container, depending on their density and
• are removed from the separation container in two vertically separate levels,

characterized,
that the starting mixture ( 12 ) of liquid ( 11 ) and the plastic chips ( 1 a, 1 b, 1 c) is fed into the apex of a conical, with its axis ( 30 ) approximately horizontal from the separating container ( 3 ), the top and bottom has conical boundary surfaces ( 32 , 33 ) to one another,
that the starting mixture ( 12 ) within the separation container ( 3 ) is moved in an almost laminar flow so that the buoyancy movement or the sinking movement of the plastic particles ( 1 a, 1 b, 1 c) overlaps with the flow movement,
that the suspended plastic particles ( 1 a) on the upper, conical boundary surface ( 32 ) and the sunken particles ( 1 b) on the lower boundary surface ( 33 ) are collected and
that at the end ( 35 ) of the separation container ( 3 ), near the two boundary surfaces ( 32 , 33 ) sorted mixtures ( 13 a; 13 c) are suctioned off. 2. The method according to claim 1, characterized in that in the flow direction before the end ( 35 ) of the separating container ( 3 ) on at least one boundary surface ( 32 , 33 ) sorted mixtures ( 13 a, 13 c) are additionally suctioned off. 3. The method according to claim 1 or 2, characterized in that the starting mixture ( 12 ) in the separation container ( 3 ) is exposed to a low-frequency vibration. 4. The method according to any one of claims 1 to 3, characterized in that at the end ( 35 ) of the separation container ( 3 ) in the region of its horizontal longitudinal axis ( 30 ) additionally sorted mixture ( 13 b) is sucked off, the plastic particles ( 1 b) have about the density of the liquid ( 11 ). 5. Device for carrying out the method according to one of claims 1 to 4, consisting of a separation container for the starting mixture,

• with an inlet for the starting mixture,
• - With an area for the swim-sink separation of the plastic and
• - with an arrangement for removing the floating and the sunken plastics,

characterized,
that the separation container ( 3 ) has a conical basic shape, the longitudinal axis ( 30 ) of which (is approximately (horizontally directed,
that the inlet ( 31 ) is arranged on the axis ( 30 ) of the conical separating container ( 3 ) at the tip thereof,
that the upper and lower boundary surface ( 32 , 33 ) form an angle between 15 ° and 35 ° to each other and
that suction pipe connections ( 321 , 331 ) are provided in each case in the plane of the upper and lower boundary surfaces ( 32 , 33 ), at the end ( 35 ) of the separating container ( 3 ). 6. The device according to claim 5, characterized in that on the upper and / or lower boundary edge ( 32 , 33 ) before the end of the conical separating container ( 3 ) additional, acute-angled to the respective boundary edge ( 32 , 33 ) intake manifold connections ( 322 , 323 , 324 ; 332 , 333 , 334 ) are arranged. 7. Device according to one of claims 5 or 6, characterized in that an additional suction pipe ( 38 ) is arranged in the region of the longitudinal axis ( 30 ) of the conical separating container ( 3 ) at the end ( 35 ) of the conical separating container ( 3 ). 8. Device according to one of claims 5 to 7, characterized in that a vibration transmitter ( 37 ) is arranged on the conical separation container ( 3 ) near the inlet opening ( 31 ). 9. Device according to one of claims 5 to 8, characterized in that a slowly rotating stator ( 36 ) is arranged in the conical separation container ( 3 ) near the inlet opening ( 31 ).