FI70939C - RENINGSFOERFARANDE FOER RETURPAPPER - Google Patents

Description

70939 Waste paper cleaning method. - Reningsförfarande för returpapper.

The invention relates to a method for cleaning waste paper according to the type definition of claim 1 and to a suitable device for carrying out the method.

Substantially prior art cleaning equipment plays a significant role in a device which, due to its mode of operation, can be described as a combined centrifugal sorter / secondary shredder, in which a closed rotationally symmetrical container generates a vortex current rotating about a generally horizontal axis for its concentric rotary axis. This eddy current makes it possible, on the one hand, to remove the species enriched with heavy impurities from the radial circumference of the eddy current and, on the other hand, in the core of the eddy stream in which the species enriched with light contaminants accumulates. Furthermore, the separation of the pulp sort takes place by means of a screen arranged outside the vortex flow behind the impeller. The screen is generally flat and is perpendicular to the axis of rotation of the impeller and eddy current.

However, a pre-cleaned waste paper fiber suspension is fed to this centrifugal sorter. This is described in GB-PS 1 340 998 with reference to Figure 3. In addition, it uses a shredder which also operates according to the eddy current principle and in which in the center of the eddy flow the packaging material, in particular strings and strips and other rotating impurities are removed together as hanging tassels. by means of a tassel thread. The pre-cleaned species is removed from the fiber suspension from the debris separated by a sieve arranged behind the rotor.

2 70939

In other currently known methods in which the removal of tassels is a so-called by means of a tassel thread, at least one other sorting device is connected between said grinder and the centrifugal sorter in order to separate, in particular, the large-surface impurities circulating before they enter the centrifugal sorter.

For this purpose, very large drums, rotating about a horizontal axis and having a perforated wall perforated, are mainly used (DE-OS 3026136). However, these are very expensive due to their necessary size. On the other hand, compensation for the initial removal of tassels is becoming more and more necessary, as this very strong tends to cause irregularity in use and severely inhibits the whole cleaning process as an essential weakness. Proper use with tassel removal is only possible if this purpose is controlled by a dedicated user.

The object of the invention) is thus to provide a safe cleaning method which also avoids a separate, high-volume and expensive, horizontal sorting drum.

According to the invention, this object is solved by a method initially mentioned by means of the features of the characterizing part of claim 1.

Particularly suitable further developments of the method are set out in claims 2 and 3.

A particularly preferred device for carrying out the method is set out in claim 5.

According to the invention, a completely new way of working of a known central exhaust separator is used. In this case, untreated, decomposed waste paper material is introduced into the device in batches at a very high concentration, whereby the material is at least partially unsuitable for pumping. This avoids all the intermediate cleaning steps that are otherwise arranged before said centrifugal sorter. This results in a very compact and reliable cleaning method. Subsequent fine cleaning steps, which were conventional in the prior art, must, of course, also be carried out in this case.

In addition to water, a suspension which has been at least partially removed from the grinder, pre-sorted and diluted can also be used as a diluent.

In the following, the invention will be described with reference to an application example shown in the accompanying drawing.

In the figure, the number 12 denotes a shredder and the number 1 a sorting device connected thereto, which has a vortex current rotating about a horizontal axis (see flow lines). In this case, the sorting device 1 representing the eddy current device is connected directly after the grinder 12 and connected to it by means of a short, large-cross-section outlet line 15. The grinding tank has a recirculation member 16 mounted on its bottom wall 28 and provided with mixing vanes 17. This recirculation member 16 rotates about an axis 26 which is only slightly inclined, i.e. inclined by a small acute angle with respect to the vertical. The lower part of the tank 12 converges and has a discharge space 29 separated from the rest of the tank space by means of a screen 18, to which a pulp discharge line 14 and a dilution water line 37 are connected. The screen 18 is inclined horizontally at the same acute angle as the recirculation member. In particular, since the discharge line 15 also removes heavy substances, i.e. high-volume and heavy-weight impurities, this line is connected to the lower part of the lower part of the tank. The same, of course, also applies to the connection of the pulp discharge line 14 in the discharge space 29.

In the described device, a high density of material 4 70939 is preferably arranged in the grinder 12, which density may be about 15 to 20%, in particular about 16%. In this case, the volume of the tank remains relatively small. Due to the improved discharge, it is therefore arranged that the dilution water is fed via the dilution water line 37 to the discharge space 29 and at least a substance content of less than 8% is produced there.

In the application example, the pulp discharge line 14 and the second discharge line 15 are provided with a flap to close them. The pulp can be removed continuously or intermittently, while the discharge line 15 for heavy materials must be opened periodically.

It is further shown that the waste paper is fed to the shredder by means of a belt conveyor device 40.

The recirculation member 16 of the shredder 12 is driven by a motor 2 by means of drive wheels 31 and 25 and drive belts. Operation is also possible via the PTO shaft.

The flaps 24 and 35 can be operated by means of hydraulic control motors, as indicated, for example, for the flap 35 by the number 27.

As the recirculation means 16, a structure with mixing vanes 17 in the form of a multi-helical conveyor coil is preferably used. Further, an embodiment in which the recirculation member 16 is arranged below the support plate 33 to mix the suspension in the lower part of the tank, especially in the discharge space, fins 32 operated by the water supplied by the dilution water line 37. In order to prevent any substantial thinning of the suspension in the grinder above the plate 33, this practically separates the underlying dilution zone 29 from the rest of the tank and the recirculation effect of the fins 32 is maintained in the former part. dam elements, such as dam walls in the vicinity of the ribs 32, arranged radially outside them.

It should also be noted that the strings and yarns of the unsorted waste paper packages which enter the shredder 12, alone or with other impurities, tend to form lumps, which, however, are automatically removed from the shredder by means of thinning water.

The biscuit sorting is indicated by the number 1 in the figure. In it, a rotor 2 rotates about a horizontal axis in front of a substantially flat screen 3, which separates the discharge space for the pulp 6 from the rest of the tank space. In this sorting device, a horizontal axial eddy current is formed, in the core of which light impurities accumulate and in the radial circumferential wall of which heavy impurities accumulate.

They can also be removed from these parts separately, especially for heavy varieties. They are removed via line 10. In the center of the sorting device, i.e. in the core of the eddy current, there is an outlet pipe A approximately in the middle, through which the varieties enriched with the light substance can be removed. Co-centrally with this pipe A, a second pipe 5 is arranged, through which the dilution water can be led close to the rotor. Since a relatively high concentration, e.g. 12%, is passed in batches via the supply line 15, the average concentration in the sorting device 1 is arranged to be about 5 S »or less by means of dilution water.

In this case, it is expedient to lead the line 15 to the end face of the sorting device and to feed the suspension practically in the axial direction into the eddy current, as shown in the figure. This affects the tearing of the high concentration waste paper batch and prevents the eddy current from slipping through with its high concentration of fiber suspensions. In this way, a relatively homogeneous eddy current is thus formed.

By means of the vortex support 7, the sleeve in the center of the rotor 2, the core of the vortex TT-6 stream enriched with light substances (foils) is made particularly clear. ^ 09 39

Suitably, as shown, the sort enriched with light soil is removed from the sorting device via the central pipe 5. The discharge of the pulp passing through the sieve from the pulp chamber 8 takes place via the line 9. For other details of the dissolution of the different varieties, reference is made to the said English patent publication.

With regard to the use of the device according to the invention, the following must be added. The flaps 35 and 24 are used appropriately and the flap 35 is necessarily intermittent.

In this case, the operating frequency of the flap 24, which is relatively pure and has a relatively low concentration of less than 10% or 8%, is correspondingly higher than the operating frequency of the flap 35. The cross-section of the line 5 at the flap 35 is also substantially larger than that of the line 14. The operation of the flap then takes place by timer-controlled methods by known methods. Corresponding devices for this time-dependent control are relatively inexpensive and also reliable. Thus, the use of the method according to the invention does not present any difficulties. Monitoring is only needed to a small extent and can be automated.

All in all, the method according to the invention achieves a simple, reliable and inexpensive waste paper cleaning process.

Claims (9)

A method for cleaning recycled paper genuinely to disintegrate the paper in a disintegrator where the content is large and by using an apparatus (centrifuge sorter) present in a substantially rotationally symmetrical, closed container by means of a substantially impeller-shaped rotor wheel vortex flow, from whose radial edge, the heavy-enriched fraction is removed and from its axial end, where the vortex flowing rotor is located, the pulp fraction is removed through a sieve adjacent to the rotor and the mean content of the vortex flow is between 3.5 %, characterized in that one of the suspension-enriched portion of the suspension, possibly only slightly diluted, in an unpumped state with a hait above 8%, is measured without sieving directly from the disintegrator in rates to the vortex flow, to which further dilution fluid is passed. 2. A method according to claim 1, characterized in that the second suspension part of the disintegrator coming from the measuring device is also measured thinned to the vortex stream. 3. A method according to claim 1 or 2, characterized in that thinning fluid is conducted at least very close to the core of the vortex stream. Method according to any of claims 1-3, characterized in that dilution fluid is conducted in the vicinity of the rotor (2) of the swirl flow device (1). 5. A method according to any one of claims 1 to 4, characterized in that the suspension is fed to the eddy current to the axial end located from the rotor (2). 6. A process according to the claim 1, characterized in that the fraction (18) removed from the disintegrator (12) is removed by means of the screen (18) removed below the rotor (16).