FR2474074A1 - METHOD AND APPARATUS FOR PRE-PROCESSING MULTI-LAYER PAPER TO RECYCLE - Google Patents

Abstract

METHOD AND APPARATUS FOR SUBJECTING CORRUGATED CARDBOARD WASTE TO A TREATMENT WITH A VIEW TO SEPARATING, BY Peeling off, the corrugated central layer from the cover layers. THE PROCESS CONSISTS OF INTRODUCING SHAPED CORRUGATED CARDBOARD FRAGMENTS IN A TANK 20 CONTAINING A BATH OF LIQUID SOLVENT CLEAN TO WEAKEN THE ADHESION BONDS AND PASS THE FRAGMENTS THROUGH THE BATH FROM INLET 30 TO OUTLET 26 OF THE TANK; TO MOVE THE FRAGMENTS TO ONE RELATIVE TO THE OTHERS WHEN THEY ARE PASSED THROUGH THE TANK, TO PENETRATE THE SOLVENT S BETWEEN THE COVERING LAYERS AND TO ADJUST THE PASSAGE TIME OF THE FRAGMENTS SO AS TO LIMIT THE ABSORPTION OF SOLVENT THROUGH THE TANK. CI BEFORE THEIR TRANSFER TO SEPARATION EQUIPMENT. THE INVENTION IS APPLICABLE TO THE RECYCLING OF CORRUGATED BOARD.

Description

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  The present invention relates to a method and an apparatus for

  to subject corrugated board to a prior treatment

  to separate it, by separation, into its various constitu-

for recycling.

  It is now well known that the recycling of waste paper (including corrugated cardboard) offers significant economic benefits and that in addition in the case

  o the waste to be recycled, that is to say the waste paper

  are of mixed types of paper, the economic interest in recycling can be further increased, often to a considerable extent, by sorting the different types of paper making up the paper.

  recovery according to their qualitative categories

  to the extent that such sorting can be carried out

before their actual recycling.

  This makes it possible to avoid or at least reduce the risk of a mixture of different types of paper during any recycling operation, a mixture which otherwise

  would require the recycled product to be

  use of low-end and consequently of low interest

  economic end. However, the preliminary sorting of the paper allows

  best types of paper to be separated and recycled in the ab-

  of low quality paper types, and

  to be used subsequently in fields of application

  high-end and therefore of higher interest.

  Machines for sorting waste paper are known and one of these is described in United States Patent No. 4,124,168. However, these machines are especially useful when sorting simple types of paper. and do not allow to sort effectively multi-layered papers of different qualities that may have

  need to be unstuck before the clean sorting operation.

so-called.

  The type of multi-layer paper, or laminate, targeted by the present invention is corrugated cardboard, often called simply "corrugated", which is used very widely,

  for example, in the field of packaging and containers.

  In its simplest form corrugated cardboard includes

  a middle or middle layer formed of rigid

  crush, which is fluted or corrugated so as to

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  present upper and lower peaks and

  you have a remarkable power of water absorption. This central layer

  trale is sandwiched between cover sheets, also called simply blankets, of another type of paper normally having a lower water absorption capacity, these covers being closely related to the tops of the central layer, usually by means of a starch adhesive.

  If corrugated cardboard was recycled in its composite form

  i0 initial site without first separating the layers, this would lead to a product comprising a mixture of the core layer material and the material constituting the covers; however, such a product is generally valuable

  relatively low and usable only in

  so-called low-end. The separate recycling of the cover sheets on the one hand and the central layer on the other hand, after separation into several layers of the corrugated board, makes it possible, on the contrary, to enhance the products from the point of view of their possibilities of use and, by therefore, to increase the value of each of the recycled products; it is even conceivable to sometimes give the central layer, which is the cheapest component, a higher value than

  corrugated waste as a whole.

  Since the separation of the constituents of the car-

  your corrugated is therefore desirable, it is subjected to a pretreatment intended to attack, or at least undermine, the adhesion bonds between its different layers so as to facilitate subsequent breakage of the links and, consequently, the separation of the respective layers during a subsequent sorting operation, thereby allowing the different types of paper or cardboard to be subsequently separated

  from each other during the recycling operation pro-

so-called.

  To the knowledge of the inventor, the only patent

  both with special reference to the separation of corrugated board layers is US Patent No. 3,833,460, in which

  which describes a so-called "dry" process. This invention

  tion can be regarded as relating to a

"wet" process.

  Theoretically, the separation of the layers of corrugated cardboard can be carried out by soaking the cardboard in a suitable "solvent", for example water, with or without additives, but, although this eventually makes it possible to effectively obtain a separation, in practice it is not possible for several reasons to proceed in such a way to soaking. Indeed, this one

  For example, there is a problem with the recovery of

  respective separate layers. The layers would be saturated with liquid and therefore less easy to sort,

  in addition, of course, the tendency to disintegrate

  and to be brought back prematurely to the state of pasta

  separation, which would, at least in part, be

  against the purpose of separation and pre-processing operations. It should be noted that the term "solvent" and its variants are used relatively freely in the context of the present invention in the absence of a better terminology for defining a substance capable of attacking and weakening, or undermining , adhesion bonds connecting the

  different layers of the corrugated board between them, this

  may be obtained by dissolving the adhesive

  or without dissolving it. Starch, for example, is an adhesive very commonly used in corrugated board and although it is not really soluble in water, which is the preferred "solvent" for starchy linkages, it is certainly sensitive to water and able to absorb it to become spongy and then tend accordingly

to lose its adhesive power.

  While recognizing that in many cases it is often

  it is desirable to initiate the separation of the layers of the corrugated board by soaking the board so as to soften the bonding bonds between its layers, the present invention generally aims to provide a method and apparatus for obtaining this result without the corrugated cardboard

  seriously risk being entirely and prematurely

born in the state of dough.

  Another object of the invention is to provide a method

  and apparatus for subjecting corrugated cardboard to

  treatment, with a view to its recycling, by putting it in a controlled manner in contact with a solvent capable of attacking the adhesion bonds in order to weaken these bonds and the

  make it susceptible to other forces exerted

  corrugated board to complete the effective separation

  ve of it and, at the same time, separate its different layers from each other for recycling. More specifically, the present invention aims to provide

  a method and apparatus for weakening adhesion bonds

  as indicated above, by introducing the corrugated waste into an appropriate solvent of the

  in the context of the present invention and by simul-

  mechanical forces on the cardboard waste on-

  to limit its adhesion bonds to the action of the solvent so that the latter are attacked and effectively weakened before the various types of paper constituting the corrugated board absorb too much

  of solvent and begin to be returned to the paste state.

  To achieve these objects, the present invention provides a method and apparatus for introducing properly cleaned and shredded corrugated board (as described later) into a liquid solvent, i.e.

  water bath; move corrugated cardboard fragments away from

  disordered with each other in the bath so as to allow the solvent to pass better between the outer layers, or covers, of the board and to expose the adhesion bonds to the solvent; continuing to move the corrugated board fragments relative to each other for a short time, sufficient for the solvent to reach, attack, soften and weaken the bonding bonds, but insufficient to initiate the process of bringing the corrugated board substantially in the paste state; of

  remove the corrugated cardboard fragments from the bath and

  free solvent before submitting them practically

  immediately to constraints in a sorting apparatus so as to break the softened bonds and to separate the different layers of the corrugated board by isolating them at the same time.

  time from each other, to recycle them.

  To allow a better understanding of the present invention, it should now be noted that the corrugated cardboard recovery is generally provided in the form called "shredded", that is to say in the form of fragments whose planar dimension exceeds rarely 650 cm2,

  the core layers of the recovered corrugated cardboard are

  usually crushed for having previously been

  driven by a baler under the gum of a bullet.

  compacted, thus providing fragments or flaps of different profiles, sizes and forms of presentation

when the ball is open.

  It should also be noted that despite a necessary cleaning

  to remove harmful or similar substances

  in the corrugated cardboard box, the constitu-

  However, their properties may remain more or less soiled in comparison with their pure initial state as a result of the different "treatments" that these constituents may have undergone during and for their initial use and as a result of which corrugated cardboard may find themselves loaded with harmful substances and relatively difficult to remove such as coatings, adhesives, printing materials and the like. In addition, although the process of the invention has proved very effective in its ability to separate

  different layers of corrugated cardboard satisfactorily

  with as little effort as possible and by reducing the corrugated board as early as possible to the pulp state, it almost inevitably

  some degree a paste fitness that also tends to

  deteriorate recycled products compared to their pure state. Finally, it should be noted that, while highly desirable, a perfectly "clean" separation is not always feasible for a variety of reasons.

  the composition of the different layers, the adhesions

  particulars used to adhere to each other, coatings and the like applied to one or

several layers, so on.

  The invention is described below in more detail with the aid of exemplary embodiments illustrated in the accompanying drawings in which: Figure 1 is an isometric view of a fragment or flap of a current form of corrugated cardboard;

  Figure 2 is a schematic side elevational view of

  than the apparatus according to the invention;

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  Figure 3 is a section along the line III-III of Figure 2; Figure 4 is a longitudinal section of the apparatus of Figure 2 along the line IV-IV of Figure 3; Figure 5 is a diagrammatic longitudinal sectional view of an apparatus constituting an alternative to that shown in Figures 2, 3 and 4; Figure 6 is a view corresponding to that of Figure 4, the apparatus being however equipped with a drainage accessory;

  FIG. 7 is a diagrammatic view, in longitudinal section,

  dinal, of a device modified with respect to that of Figure 5; Figure 8 shows, in graphical form, the amount of water absorbed and the ease of separation of the layers of the corrugated board as a function of time; and FIG. 9 represents, also in graphical form, the effects of various operating parameters on the time required to obtain easy separation.

layers of corrugated cardboard.

  It is hardly necessary to specify that the apparatus is represented, for the sake of clarity and for a better understanding of the invention, schematically and not

  not as it would be built for industrial purposes.

  It is also to facilitate understanding that the.

  method and apparatus are described below, in some respects, not separately but together, so that the

  process is sometimes highlighted by the description of

  the device which in turn is sometimes better elucidated

by the description of the process.

  Given that the corrugated cardboard can be in a variety of forms, which are also quite common, the invention is described below by taking as an example the corrugated cardboard which is of the simple and well known type having a central layer 2 formed generally from

  semi-chemical fibers and laminated to sheets of

  4.4 in unkempt kraft fiber using a water-sensitive starch adhesive capable of forming bonds 6 at which the covers 4.4 are in contact with the

  vertices 6 'of the corrugations 8 and are subject to these vertices.

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  In the normal, uncrushed state of corrugated cardboard, the corrugated

  8 thereof form grooves or channels 10 through which the links 6 can easily be reached by

  the liquid in which the corrugated cardboard is immersed. Toute-

  However, the corrugations 8 will generally be crushed during the baling of the recovery cardboard and, although this is likely to make the links 6 less accessible, the widespread dislocation of corrugated cardboard, also due to baling, will tend to allow the corrugated board to undergo more the action of the solvent or to better absorb it so as to compensate more or less the tightening

  caused by the collapse of the Canals 10.

  Since, as already explained, the central layer

  2 is more easily saturated with liquid than

  4, the invention aims above all to allow the links 6 to be wetted to a maximum in a period of time also

  as short as possible so as to reduce to a minimum the impregna-

  hedging 4 and thereby delaying the process

  bringing them back to the state of dough.

  Accordingly, the present invention provides a method of introducing pre-cleaned corrugated cardboard, in shredded form, into a liquid solvent-described later and moving the corrugated cardboard fragments in a disordered manner with respect to one another in the solvent. of

  in order to make them flex and topple, change their orientation

  tion, to flip them over and, in a general way, to pass them continuously from one place to another, not only to expose new parts of the fragments to the solvent, but also to make the adhesion bonds 6 as much as

possible accessible to the latter.

  A convenient and very simple way to perform this

  phase of the treatment consists of placing the solvent in a

  an elongate container having its axis arranged horizontally, this container being able for example to be one of the tanks represented

  in FIGS. 2 to 7. A tank of this type can be constituted

  killed by the rotary tubular drum 20, shown for

  side of FIG. 2 and in cross-sectional or longitudinal

  dinal in other figures, which has at its ends walls 22 in which there are provided central openings 24, 26 respectively for the introduction

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  corrugated cardboard fragments C in the drum 20 and at the

out of these fragments of the drum.

  The drum 20 is intended to form a medium in the

  which corrugated cardboard fragments C can be conveniently

  bathed in the liquid solvent, the nature and particular character of which necessarily depend on the specific adhesive used for laminating the type of

  corrugated cardboard C to be processed and must, as far as possible,

to this adhesive.

  As indicated previously, ordinary starch is an adhesive very widely used for this purpose and is at the same time sensitive to an aqueous solvent which tends to soften it and reduce the persistence of its adhesive power. As we

  the effects produced by such an aqueous solvent on the amine

  donations can obviously be accentuated under certain conditions by the addition to this solvent of a wetting agent, such as urea or alkoxylated polyalkylphenol marketed

under the trademark Triton X-100.

  Thus, in the present embodiment, the liquid solvent S contained in the drum 20 between its walls 22 is water (with or without additives) which can be refueled from time to time as required by pouring 28 liquid through the opening of one of the walls 22 or, if

  where appropriate in the filler neck 30.

  It should now be emphasized that the efficiency of the process according to the invention depends on several factors to a greater or lesser degree depending on the particular type.

of corrugated board C to be treated.

  Thus, the solvent S used must not only be best suited to the adhesive used for laminating the cardboard

  corrugated C, but it is also necessary to regulate its temperature se-

  certain treatment parameters such as, for example, the exposure time of the corrugated board C to the solvent, that is to say

  his residence time in the latter.

  Other factors, such as the size of the fragments, the more or less energetic way of moving them by

  others, etc. can also play a role.

  however, these parameters are not quite as important

  tants as the solvent, the temperature of it and the time

stay.

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  In the first example, the filler neck 30 is arranged to empty into the drum 20 through an opening 24 in one of the walls 22; this opening thus constitutes the entry point of the shredded corrugated cardboard C into the drum 20 while its exit point is the opening

  discharge 26 formed in the wall 22 opposite.

  The residence time of the corrugated board C is the duration of its transit between its point of entry and its exit point of the drum 20 and it is obviously possible to use several means to advance the corrugated cardboard fragments C

between these two points.

  For example, the residence time may be influenced by the flow rate of the corrugated cardboard fragments C entering the drum 20 as well as by the speed of rotation of the latter,

as explained below.

  As shown in FIG. 6, fragments of corrugated cardboard C brought rapidly into the drum 20 tend to accumulate near the opening 24 where they first fall out of the filler neck 30. However, the accumulation of fragments of corrugated cardboard naturally tends to level when the drum 20 rotates, this rotation at the same time to obtain several other favorable effects. Indeed, the rotation of the drum 20 tends to cause the lower layers of corrugated cardboard fragments C and lift them out of the liquid solvent bath at the bottom of the drum 20 to then fall again on the pile accumulated fragments, thus allowing

  upper layers of the pile to find place and to be im-

  merged into the solvent, substantially as shown in

figure 3.

  Likewise, the rotation of the drum has the effect of

  the corrugated cardboard fragments in relation to the

  others and to change their orientation, bringing new

  surfaces of the fragments in contact with the solvent, as well as to pass them continuously from one place to another so as to promote the flow of the solvent S through the channels 10 of the central layer 2. Thus, in a manner

  In general, the rotation of drum 20 will have the effect of displacing

  Corrugated cardboard fragments C in relation to each other

  others in the drum and to communicate to them different

  such as sagging, tilting, tumbling,

  pouring, etc., so as to make the solvent back and forth in the channels 10 and thus allow it to access as easily as possible adhesion bonds 6. The displacement of corrugated cardboard fragments C the

  vis-à-vis others as well as their advancement

  drum 20 may also be favored or ob-

  kept entirely by the provision of finned fins or pallets

  paces 32 mounted longitudinally on the inner wall 34 of the drum so as to rotate therewith. Obviously, the corrugated cardboard fragments C in the drum-20 are periodically raised by the rotary pallets 32 which then let them fall again so as to move and redistribute them constantly. Moreover, by conferring

  to the pallets 32 mounted on the wall 34 of the drum an inclination

  More or less diagonally or spirally in an appropriate direction, corrugated cardboard fragments C are allowed to move in the required manner as they move.

  against each other as indicated above.

  As a result, all corrugated cardboard fragments C

  introduced into the rotary drum 20 are in

  immersed satisfactorily in the liquid solvent

  Contained in the drum and are at the same time forced to

  from their point of entry into the drum 20 to their point of

exit from it.

  Therefore, the rotation of the drum 20 serves not only

  It is also necessary to put the corrugated cardboard fragments C better in contact with the liquid solvent S, but also to enable them to advance between the two points mentioned. While being very effectively used for this purpose, however, a rotating drum is not the only means available for moving corrugated cardboard fragments C relative to each other and moving them in a solvent bath. In fact, the same purpose can be achieved by using the relay transfer system illustrated schematically in FIG. 5 and comprising a non-rotating tank 120 for a solvent bath P and a series of paddle wheels 40

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  cooperating with each other and mounted one after the other between the filling chute 130 and the outlet point 126 of the tank 120. It goes without saying that the corrugated cardboard fragments C entering the tank are received first by the first impeller 40 and are transferred thereto to the next and so on until they reach the exit point 126. In this embodiment, the blades 42 of each paddle wheel perform a course of travel. arc partially located in'an bath P contained in the tank 120, so that the corrugated cardboard fragments C are

  not only constantly redistributed but also succes-

  repeatedly immersed in the solvent

  being received and transferred as described above.

  The illustrated and described embodiments

  attempt to move the corrugated cardboard fragments C relative to each other and advance them in a bath of solvent to allow it to access the links 6 connecting the covers 4 to the central layers 2 of the fragments of corrugated board C and to adjust the residence time, it being understood that this is also variable in

  function of the distance to be traveled by the fragments of car-

  corrugated tone between their entry and exit points as well as

  by the speed of the particular advancement mechanisms used

  his. Generally, the free solvent S remaining trapped in the channels 10 of the core layer 2 flows wholly or largely from it during the agitation that the corrugated cardboard fragments C can undergo while being removed from the solvent S and transferred to the separation and sorting apparatus. However, positive drainage can be achieved by subjecting the corrugated cardboard fragments C to treatment

  mechanical drainage carried out for example in a rotating cage

  50 is schematically shown in section in FIG. 6 and arranged to receive the fragments coming out of the

drum 20.

  The cage 50 may or may not be equipped with fins 132 corresponding to the fins 32 of the drum 20; this is why the cage shown in Figure 6 is broken into two parts

  respectively provided and without fins.

  The cage 50 can be rotated to allow the

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  fragments of corrugated cardboard C which are supplied to him by the

  dipping agents to be moved in a disordered manner with respect to each other; by undergoing these displacements the corrugated cardboard fragments dispose of the free solvent as they advance into the cage 50 from the exit end of the drum 20 at the outlet end 52 of

the cage 50.

  Another drainage means is represented in the form of the chain conveyor 60 of FIG. 5 on which buckets 62 are mounted and which is located at the outlet end of the tank 120 to collect corrugated cardboard fragments C of the last impeller 40 and drive upward outside the liquid solvent S at a location outside the tank 120 o they fall from the carrier; the

  liquid solvent S entrained by the corrugated cardboard fragments

  can fall back through bucket conveyor 60 into the

  tank 120 or in the collecting tank 64 to be returned to the

  lation. The equipment 70 mounted in the tank 220 (FIG. 7) to drive the corrugated cardboard fragments below the level of the liquid can, if the circumstances lend itself to it, replace the series of paddle wheels of FIG. 5 and is also equipped. blades 72 which are fed with corrugated cardboard fragments C by the filler neck 230-and through which the fragments are then pushed through the liquid solvent

  S in the tank 220 towards the outlet end 226. While may not act as vigorously as the drum

  20 or the relay transfer system of Figure 5, the bucket conveyor 60 of Figures 5 and 7 and the equipment 70 of Figure 7 for training

  fragments of corrugated cardboard under the liquid level

  nevertheless put in pieces of corrugated cardboard C during

  their transit through tanks 120 and 220 and outside those

  to be agitated to a greater or lesser degree to achieve the object of the invention as a function of various factors

  such as the average size of corrugated cardboard fragments.

  The motor M of FIG. 2 drives wheels W which turn the drum 20 and can also drive the moving members of FIGS. 5 and 7. The motor M or the transmission members (not shown) normally and

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  usually associated with this motor can be adjustable

  in order to vary the speed of the team-

  and thus to obtain the desired residence time of the corrugated cardboard fragments C in the solvent S. Some operating parameters relating to the preliminary treatment of the corrugated cardboard fragments were studied in

  model conditions using the test math de-

written below.

  Corrugated cardboard having on each side a single cover sheet (the basic weight ratio between

  layers being 42/26/42) and laminated by means of a

  starch-based sif is cut into ribbons measuring 150 mm (perpendicular to the flutes) over 15 mm. Ribbons

  are immersed for a fixed period of time in the soil.

  treatment and are subjected to separation using an Instron dynamometer within one and a half

after removal of the solvent.

  The resistance to separation is measured as the average force required to break the bond between the

  peaks of the middle layer and the cover sheet.

* Each value is the result of tests performed on at least five ribbons and from 8 to 10 measurements recorded per ribbon. The moisture content of the ribbons is determined immediately

  after oven drying tests.

  "Reference" conditions are defined as

  carrying the use of water at 20VC without additive as

treatment solvent.

  Resistance values at separation of fragments

  corrugated board obtained under different processing conditions

  Figure 1 shows the variation in separation resistance as a function of treatment time under reference conditions. At time zero, the resistance to separation is substantially greater than the mechanical strength of the different layers of the corrugated board and there is a tearing of

  these layers. Separation is considered "easy" when

  that the resistance falls to an arbitrary value of 60 grams in the test method described above because treated corrugated cardboard waste is generally subjected to at least as great a force during their implementation

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  subsequent in a fiber classifier. In the

  reference treatment conditions separation occurs easily after about 50 seconds of immersion (point A). The moisture content of the treated corrugated cardboard fragments is shown in FIG. 9. It is observed that under the reference conditions the moisture content increases in a moderately rapid manner during the period of time.

  at the end of which the separation becomes easy (curve 1, point A ').

  It is conceivable that, despite the fact that no data is provided in this respect in the context of the present invention, the mechanical strength of the various layers in the wet state decreases as the content of their contents increases.

  water as a function of time. In the reference conditions

  it is found that the mechanical strength of the layers in the wet state can become almost zero, as evidenced by the disintegration experienced by the layers after about five minutes of immersion. There is then a difference between the time required for an "easy" separation and the one at the end of which the decay of the layers of the corrugated board occurs.

  In practice, this difference in time can be increased

  by removing the corrugated board from the treatment bath before the lapse of time after which the separation becomes

  Easy. Solvent entrained by the corrugated board continues to

  jogging the adhesion bonds between the layers and

  to obtain resistance to separation. Part of the entrained solvent may be separated from the corrugated cardboard fragments by the means described for this purpose. Another part of the solvent penetrates the corrugated board so as to increase its moisture content and thereby reduce its resistance to

  wet state. However, while the resistance to separation

  The amount of solvent available for imbibition can usually be adjusted so that it does not reach the level required to saturate.

  completely the layers and lead to their disintegration.

  Said difference in time may also be

  surrounded by the temperature of the treatment bath and the

  used. In FIGS. 8 and 9, the values obtained

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  for a bath temperature of 100C are represented by curve 2. In this case the time required to obtain easy separation is obviously increased, this time being then 1.3 minutes (point B, figure 8). Surprisingly, the moisture content of the corrugated board at the end of the treatment time required to obtain a

  easy separation (point B ', Figure 9) is significantly lower than

  than that of the witness, that is to say fragments of car-

  corrugated tone treated under the reference conditions, which

  indicates that said time difference is increased.

  It should also be noted that it is advantageous to reduce the amount of solvent entering the

  which will generally be used in combination with

  similar treatment according to the invention.

  Reference conditions were further changed by using as the solvent water containing 0.004% by volume of a nonionic surfactant (Triton X-100, commercial designation of an alkoxylated polyalkylphenol), the temperature of the bath being maintained at 20OC. The values thus obtained are represented in FIGS. 8 and 9 by

  curve 3. The time required to obtain a separation

  in this case is reduced (point C) in comparison

  because of the result obtained under reference conditions.

  While the speed of moisture absorption by the carton

  corrugated evolves substantially as for the witness, that is,

  the corrugated cardboard fragments processed under the conditions

  benchmarks, the moisture content of corrugated cardboard at

  stage of easy separation (point C ') is

  than that of the witness, again indicating that in these

  conditions the difference between the time required to obtain

  of easy separation and that at the end of which

  layers of corrugated cardboard disintegrate, is increased.

  Finally, it should be noted that the forms of

  illustrated and described in detail do not present any

  limiting character and that it is quite conceivable to use

  to find other ways to implement the principles

  of the present invention without departing from its scope.

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Claims (18)

  1. Process for pre-treating paper or corrugated board   several layers in order to separate its central layer on-   characterized in that it comprises the steps of - introducing corrugated cardboard waste in a shredded form into a vessel containing a bath of liquid solvent suitable for weakening the coatings of the cover layers to which it is connected by adhesion bonds, bonding bonds, and advancing corrugated cardboard fragments through the bath from an entry point to an outlet point of the vessel;   - move the pieces of corrugated board in a de-   skewed against each other as they   pass from the point of entry to the exit point in order to   riser the penetration of the liquid solvent between the cover layers and allow it to better access the adhesion bonds;   - adjust the transit time of the pieces of cardboard on-   dule in the tank so as to allow proper weakening of the bonding bonds while limiting as much as possible the amount of liquid solvent absorbed by the various layers of the corrugated board; - and remove the corrugated cardboard fragments from the tank at said exit point, and transfer them to equipment to separate their layers while   adhesion bonds are weakened.   Process according to Claim 1, characterized in that the vessel is rotated in order to move the corrugated board fragments in a disordered manner. compared to others.   Process according to Claim 1, characterized in that the corrugated cardboard fragments pass into the tank of the inlet-outlet of the latter by means of a system relay transfer.   4. Process according to Claim 1, characterized in that the corrugated cardboard fragments are pushed through the bath to advance them.   5. A method according to claim 1, characterized in that the corrugated cardboard fragments are freed of free liquid solvent before removal from the tank and   after their transfer to the repair equipment.   6. A method according to claim 2, characterized in that the corrugated cardboard fragments are accumulated at the moment and at the point of their entry into the tank and are advanced to the point of exit thereof by the rotation of the tank.   7. Process according to Claim 5, characterized in that the corrugated cardboard fragments are transported in   a direction with an ascending slope in order to get rid of liquid solvent book.   8. Process according to claim 5, characterized in that the corrugated cardboard fragments are rotated.   in a cage to rid them of liquid solvent.   9. A method according to claim 6, characterized in that the tank is rotated about its axis and the corrugated cardboard fragments are received in a cage at which they exit the tank, which cage is rotated in order to move corrugated cardboard fragments in a disordered manner and free from free liquid solvent before   transfer to separation equipment.   Process according to Claim 7, characterized in that the corrugated cardboard fragments are collected from the bath at said outlet point and are removed from the tank in a direction with an upward slope and thus fed   at a point outside the tank.   11. Apparatus for pre-treating corrugated board for   to separate its corrugated central layer from the layers of   to which it is connected by adhesion bonds, characterized in that it comprises: - a tank having an inlet for corrugated cardboard fragments and an outlet for them which is located at a certain distance from the entrance the tank being adapted to contain a liquid solvent bath through which the corrugated cardboard fragments can pass from the inlet to the outlet, and a means for moving the corrugated cardboard fragments into the bath and advancing them entrance to the exit.   12. Apparatus according to claim 11, characterized in that the vessel is a drum rotatable for   move corrugated cardboard fragments disorderedly   relative to one another and to advance them in said direction, members being provided which make it possible to rotate the drum at a speed limiting the residence time.   fragments of corrugated cardboard in the drum.   13. Apparatus according to claim 11, characterized in that it comprises:   a first impeller arranged so as to re-   see fragments of corrugated cardboard introduced into the tank at the entrance and send them into the bath; - another paddle wheel arranged to collect the corrugated cardboard fragments of the bath and to bring them to the exit; and members arranged between these two paddle wheels and making it possible to transfer the corrugated cardboard fragments by a relay system from one to the other of these two wheels paddle.   14. Apparatus according to claim 11, characterized in that it comprises an endless conveyor which, capable of driving the corrugated cardboard fragments within the solvent bath and capable of continuously rotating between the inlet and the outlet, is equipped with receiving elements arranged to successively receive fragments of corrugated cardboard introduced into the tank at the inlet and to the   pass through the bath towards the exit.   15. Apparatus according to claim 11, characterized   in that it includes an organ for picking up fragments   corrugated board to the outlet, out of the tank by transporting them up to a point outside the tank to leave them then fall.   Apparatus according to claim 11, characterized   in that it comprises a cage in which the corrugated cardboard fragments can be received at said outlet and which can be rotated to allow the corrugated cardboard fragments to be better freed of free solvent.   17. Apparatus according to claim 12, characterized in that pallets are provided on the inner wall of the drum for winding the corrugated cardboard fragments and   let them fall while the drum is spinning.   Apparatus according to claim 13 or 14, characterized   characterized in that it comprises a member for picking up corrugated cardboard fragments brought to said outlet, pulling the corrugated cardboard fragments out of the tank up to a point outside the chamber.   tank to make them fall back then.