(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2010/0194005 A1
`Toncelli
`(43) Pub. Date:
`Aug. 5, 2010
`
`US 2010.0194-005A1
`
`(54) METHOD AND APPARATUS FOR
`MANUFACTURING SLABS WITH VENED
`EFFECT
`
`(76) Inventor:
`
`titles Bassano Del Grappa
`
`Add
`d
`C
`orrespondence Address:
`INTELLECTUAL PROPERTY GROUP
`FREDRIKSON & BYRON, PA.
`200 SOUTH SIXTH STREET, SUITE 4000
`MINNEAPOLIS, MN 55402 (US)
`
`(21) Appl. No.:
`
`12/669,121
`
`(22) PCT Filed:
`
`Jul. 4, 2008
`
`(86). PCT No.:
`
`PCT/EP2008/058682
`
`S371 (c)(1),
`(2), (4) Date:
`
`Jan. 14, 2010
`
`Foreign Application Priority Data
`(30)
`Jul. 16, 2007 (IT) .......................... TV2OO7AOOO126
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`C04B 33/30
`(2006.01)
`B29C 47/04
`52) U.S. Cl. ......................................... 264/650: 425/104
`(52)
`s
`(57)
`ABSTRACT
`During the manufacture of slabs with a veined effect a liquid
`or powder colouring agent is deposited on the Surface of a thin
`layer of starting mixture by means of at least one dispensing
`device (40) and the resultant mixture is supplied, falling
`freely, from one end of an extractor belt (30) forming the
`bottom of a mixture metering/distributor unit, following
`which the mixture is transferred, falling freely, onto a tempo
`rary moulding Support (14). This results in the production of
`slabs provided with veining extending through the entire
`thickness of the slabs and also visible along the whole edge of
`the slab, even after it has been machined.
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`22
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`28
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`2O
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`4 O
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`a b c d e f g h i
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`l m ri
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`Fig. 3
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`Patent Application Publication
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`US 2010/0194-005 A1
`
`Aug. 5, 2010
`
`METHOD AND APPARATUS FOR
`MANUFACTURING SLABS WITH VENED
`EFFECT
`
`0001. The present invention relates to the manufacture of
`conglomerate stone slabs obtained from mixtures consisting
`of granules of stone and/or stone-like material and a bonding
`agent, and more specifically to the manufacture of slabs of
`this type which have particular colouring effects, such as
`so-called veining, intended to imitate as closely as possible
`natural Stone materials.
`0002 More specifically the invention relates to a method
`and an apparatus for producing the slabs in question. In the
`description which follows reference will be made to the pro
`duction of slabs with a veined effect, it being understood that
`reference thereto is made solely by way of a non-limiting
`example.
`0003 For many years so-called Bretonstone slabs have
`been known, this name referring to a particular manufactur
`ing technology which essentially envisages the preparation of
`one or more starting mixtures comprising granules of Stone
`and/or stone-like material with a specific particle size distri
`bution and a bonding agent which made be of an inorganic
`nature (such as cement) or a synthetic resin which can be
`hardened (by the action of heat and/or a catalyst).
`0004. The starting mixture is distributed in the form of a
`layer of predetermined thickness on a temporary moulding
`Support (such as a conveyor belt or a tray mould) and then
`Subjected, for a predefined period of time and under a vacuum
`of given intensity, to the action of a press while a vibratory
`movement of prechosenfrequency is applied to the press ram.
`0005. The resultant rough-formed slab is then transferred
`to the hardening stage using procedures which depend on the
`nature of the bonding agent.
`0006. In the continuation of the present description refer
`ence to Bretonstone slabs and/or the Bretonstone method is
`understood as meaning slabs obtained with the method
`described above.
`0007 According to an already known method for manu
`facturing Bretonstone slabs with a veined effect, after the step
`involving deposition of the starting mixture on the temporary
`Support, colouring agent is distributed in an irregular manner
`on the surface of the layer of mixture and then the colouring
`agent is mixed up with the mixture using a spiked tool so that
`the colouring agent penetrates into the thickness of the mix
`ture to a depth such that the finished slab, after the usual sizing
`and polishing operations, has veining similar to that of the
`natural stone from which the granules used in the mixture are
`obtained.
`0008 For further details regarding this method and the
`associated apparatus reference should be made to the patent
`IT-A-1,328.246 (corresponding to WO-A-03/027042) in the
`name of the same applicant, herein incorporated by reference.
`0009. This method is useful solely in the case where the
`finished slab must not be used such that its side edges are
`visible.
`0010. In fact, it has been found that, no matter how effec
`tively mixing up of the colouring agent may be performed by
`means of the spiked tool, the colouring agent penetrates into
`the thickness of the mixture—and can therefore be seen in the
`finished slab-only over a section of a few millimetres, cor
`responding to not more than half the thickness of the finished
`slab.
`
`0011. There exist, however, certain uses of the finished
`slabs where the edge or side of the slab also remains visible
`(as, for example, in the case of so-called kitchen or bathroom
`tops) and, after polishing, the veining can be noted only in a
`thickness of a few millimetres from the top surface, while it is
`absent in the remainder of the edge or side to the detriment of
`the aesthetic characteristics of the slab laid.
`0012. According to an alternative solution, also known,
`for obtaining Bretonstone slabs with a veined effect, the mix
`ture is distributed on the moulding Support by means of a
`weighing type distributor unit with the characteristic features
`described in the patent IT-A-1,335,533 (corresponding to
`WO-A-2004/039547), herein incorporated by reference.
`0013. In this case, the starting mixture, before being
`loaded into the metering unit, is made to pass underneath
`devices which apply liquid or powder colouring or pigments
`agents onto its surface.
`0014 Since the mixture is loaded into the metering unit,
`falling freely, and then conveyed to the outlet for discharging
`onto the moulding Support, it undergoes a certain degree of
`remixing which in turn results, on the one hand, in a Substan
`tial shortening of the veining and, on the other hand, in a not
`insignificant diffusion of the pigment in the mass of the mix
`ture which is therefore at least partly coloured throughout the
`a SS.
`0015. Another technology known for many years and
`aimed at the manufacture of slabs designed for internal and
`external cladding of buildings as well as the manufacture of
`articles similar to ceramic articles is one where granules of
`stone, Stone-like or ceramic material, preferably in the form
`of sand, with a suitable particle size distribution, are mixed
`with the components normally used for the manufacture of
`ceramic materials, usually in powder form, and consisting
`mainly of clay or kaolin.
`0016. The resultant mixture is wetted with a bonding
`agent, which may be sodium silicate in aqueous form or a
`mixture of silicasol and polyvinyl alcohol.
`0017. With this starting mixture a layer of predetermined
`thickness is formed on a temporary Support which is then
`Subject to a vibrocompression step, resulting in a rough
`formed slab.
`0018. The slab, after a drying step, in order to remove the
`water present in the mixture, undergoes abaking step at a high
`temperature (in the region of 1200° C.).
`0019 Below this technology, the associated method and
`the resultant slabs will be referred to by the generic name of
`“Lapitech'.
`0020. This type of slab and technology is also affected by
`the same problem already mentioned with regard to the Bre
`tonstone slabs.
`0021. It is therefore desirable to provide a method and a
`corresponding apparatus for manufacturing slabs of the Bre
`tonstone or Lapitech type in which the slabs have coloured
`veining with a length comparable to that of standard natural
`stone and this veining is visible throughout the thickness and
`therefore along the entire edge of the finished slabs.
`0022. This object is achieved with a method for manufac
`turing slabs in which:
`0023 at least one starting mixture comprising at least one
`granular product comprising Stone or stone-like or ceramic
`material with a specific particle size distribution and a hard
`ening bonding agent is prepared:
`
`

`

`US 2010/0194-005 A1
`
`Aug. 5, 2010
`
`0024 said at least one mixture is loaded into a metering/
`distributor unit comprising:
`0025 a hopper with a top mouth for loading the mixture
`and a bottom opening for discharging the said mixture;
`0026 an extractor belt which forms the bottom wall of said
`hopper,
`0027 the mixture discharged from the bottom opening of
`said hopper is transferred by means of said extractor belt so
`that, falling freely from said belt, it is distributed in the form
`of a layer of predetermined thickness on a temporary moul
`ding Support positioned at a lower level than said extractor
`belt;
`0028 the layer of mixed formed on said temporary Sup
`port is Subjected to vibrocompression so as to obtain a rough
`formed slab;
`0029 after a drying step, where applicable, said rough
`formed slab is transferred into a hardening station,
`0030 the method being characterized in that at least one
`colouring or pigmenting agent is distributed on the Surface of
`the mixture being transferred by means of said extractor belt
`before the mixture is distributed, falling freely, onto said
`temporary moulding Support.
`0031 Advantageously, the metering/distributor unit used
`in said method is that described and illustrated in Italian
`patent application No. TV 2004AO00118 (corresponding to
`WO-A-2006/045728), herein incorporated by reference.
`0032. In the case where Bretonstone slabs are manufac
`tured, the method according to the present invention envis
`ages that: the bonding agent contained in the at least one
`starting mixture may be of an inorganic nature (such as
`cement) or a synthetic resin which can be hardened (by the
`action of heat and/or a catalyst); the layer formed on said
`temporary moulding Support is Subjected, for a predefined
`period of time and under a vacuum of given intensity, to the
`action of a press, while a vibratory movement of prechosen
`frequency is applied to the press ram; the resultant rough
`formed slab is subjected to the hardening step using proce
`dures which depend on the nature of the bonding agent.
`0033. In the case where Lapitech slabs are manufactured,
`where said starting mixture (as already mentioned) com
`prises, in addition to the granules of Stone, Stone-like or
`ceramic material with a prechosen particle size, in particular
`in the form of sand, also materials known per se for the
`manufacture of ceramic materials, such as clay and kaolin in
`powder form and an agent chosen from Sodium silicate and
`silicasol together with polyvinyl alcohol, the rough-formed
`slab resulting from the vibrocompression step is Subjected to
`a drying step and then a high-temperature baking step Such
`that the clay or kaolin forms a bonding matrix for the above
`mentioned granules.
`0034. In the preferred embodiment of the invention said at
`least one colouring agent is distributed on the Surface of the
`mixture in a non-uniform manner.
`0035. In turn the apparatus according to the invention is
`that described in the already cited Italian patent application
`No. TV2004AO00118, except that it comprises as a charac
`terizing aspectat least one device for dispensing colouring or
`pigmenting agent positioned at the downstream end of the
`extractor belt forming the bottom of the already mentioned
`hopper so as to dispense said colouring agent onto the Surface
`of the layer of mixture transported by means of said extractor
`belt towards the position where it falls freely onto the said
`temporary moulding Support.
`
`0036. It has been established that with the method and the
`apparatus according to the present invention the colouring
`agent is distributed randomly and not uniformly within the
`mass mixture, which falls into the temporary Support produc
`ing the aforementioned veining which affects the entire thick
`ness of the finished slab.
`0037. The colouring or pigmenting agent may be in solid
`form (preferably a dry powder) or liquid form and may be
`supplemented with or replaced by colouring or reflective
`granules which result in very attractive special effects in the
`finished product and throughout its thickness.
`0038 Considering now specifically the colouring agent
`dispensing device associated with the abovementioned appa
`ratus, it may comprise a plurality of devices, namely one for
`each colouring agent, which are controlled independently of
`each other as regards the start and end of the dispensing
`operation, which may take place continuously or intermit
`tently.
`0039. In the case where there is a plurality of dispensing
`devices, they may be mounted transversely with respect to the
`direction offeeding of the extractor belt which transports the
`layer of mixture discharged by the metering/distributor unit,
`so as to cover the entire width of the mixture layer.
`0040 Alternatively, it is possible to envisage a smaller
`number of dispensing devices mounted on a cross-member
`fixed at the top and transversely with respect to the extractor
`belt for the layer of mixture and movable along the said
`cross-member.
`0041. The invention will now be described with regard to
`the accompanying drawings which show, by way of a non
`limiting example, two variations of embodiment of the appa
`ratus according to the invention.
`0042. More specifically:
`0043 FIG. 1 is a front view of the apparatus provided with
`a plurality of units for dispensing colouring or pigmenting
`agents according to the invention;
`0044 FIG. 2 is a partially sectioned side view of the appa
`ratus according to FIG. 1;
`0045 FIG. 3 is a side view of solely the mixture metering/
`distributor unit equipped with a device for dispensing colour
`ing agent in powder form according to a first embodiment of
`the invention which is also visible in FIG. 2;
`0046 FIG. 4 is a view similar to that of FIG.3 of a device
`for dispensing liquid colouring agent according to a second
`embodiment of the invention which is also visible in FIG. 1;
`0047 FIGS. 5 and 6 are axonometric views of products
`which can be obtained with the present invention.
`0048 FIGS. 1 and 2 show an apparatus according to the
`present invention for distributing, in the form of a thin layer,
`on a Support used in a plant for producing stone articles, a
`mixture based on agglomerate Stone or ceramic material, to
`which colouring Substances are added depending on the pre
`determined aesthetic effects.
`0049. In brief, the apparatus comprises a frame 10 which
`Supports a Surface 12 on which a temporary moulding Support
`14 is placed for each operating cycle, on which Supportalayer
`of mixture 18, supplied by a metering/distributor device
`denoted overall by the referenced above 20, is deposited in a
`free-falling manner.
`0050. The mixture distributor 20 in turn comprises a hop
`per 22 with a top mouth 24 for loading fresh mixture, a shaped
`or conveying wall 26 with a profile curved towards the inside
`of the hopper 22 and a mixture discharge opening 28 at the
`end of said shaped wall 26.
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`

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`US 2010/0194-005 A1
`
`Aug. 5, 2010
`
`0051. An extractor belt 30, positioned underneath said
`hopper 22, forms with its upper surface 30 the bottom of said
`hopper.
`0052. The belt 30 is used to convey and deposit a uniform
`layer of said mixture, after it has flowed inside the hopper 22
`and passed out through said discharge opening 28, on said
`temporary support 14 which is positioned at a lower level than
`said extractor belt. At the same time a relative movement of
`said hopper 22 and said Support 14 is maintained so that the
`layer of mixture distributed on said support is uniform.
`0053. In order to ensure the relative movement of hopper
`22 and temporary Support 14, the metering/distributor device
`20 is mounted on a carriage denoted overall by the reference
`number 34 and movable by means of roller wheels parallel to
`the Surface 12 of the apparatus.
`0054 From FIG. 1 it can be readily understood how the
`distribution and metering hopper 22, the extractor belt 30 as
`well as the mixture discharge opening 28 extend Substantially
`over the entire width of the surface 12 so that the resultant
`product is a slab which has notable dimensions not only
`lengthwise but also transversely. In this connection it is worth
`noting that the slabs which can be obtained with this technol
`ogy may have and in reality also have widths greater than 1.5
`metres and lengths greater than 3.3 metres.
`0055 For further details regarding this apparatus refer
`ence should be made to the already mentioned Italian patent
`application No. TV2004A000118.
`0056. According to the invention, at least one device for
`dispensing colouring agent, denoted by the general reference
`number 40, is positioned at the downstream end of the extrac
`tor belt 30, preferably downstream of the discharge opening
`28 of the hopper 22.
`0057. In this connection it should be noted that the colour
`ing agent may be dispensed at any point on the upper Surface
`32 of the extractor belt 30, except for the Zone immediately
`underneath the hopper 22.
`0058. In particular, in accordance with the embodiment
`shown in FIGS. 1 and 4, at the downstream end Zone of the
`extractor belt 30, the carriage 34 has, mounted thereon, a
`Support structure comprising a cross-member 36 with, fixed
`thereto, a plurality of devices for dispensing colouring
`agent—denoted by the reference numbers 40(a-m), respec
`tively—each of which has a nozzle intended to emit a con
`tinuous or discontinuous jet of colouring agent (which, as
`ready mentioned, may be liquid or in the form of dry powder)
`which strikes a strip of the layer of mixture deposited on the
`tray mould, so as to cover overall the entire width of the
`mixture.
`0059. As regards the structure of the colouring agent dis
`pensers, it is preferably that described in the aforementioned
`Italian patent application TV2004AO00118 and illustrated in
`FIGS. 2 and 3 thereof.
`0060. The surface of the mixture, before leaving the
`extractor belt 30, is therefore sprinkled with colouring mate
`rial in a manner which depends on the operating mode of the
`dispensing nozzle. In fact, if the dispensing nozzle is operated
`intermittently and at irregular time intervals, it is evident that
`the distribution of colouring agent on the Surface of the mix
`ture will not be homogeneous and pre-ordered.
`0061 Since the mixture with colouring agent is then trans
`ferred by means of a free-falling action onto the temporary
`moulding Support and since the mixture when falling pro
`duces coloured lumps on the Surface, the colouring agent,
`without uniformly colouring the mixture, is able to produce
`
`during the Subsequent vibrocompression step colouring
`effects which affect the entire thickness of the manufactured
`article, similar to the veining of natural stones.
`0062) If, on the other hand, the mixture were to be uni
`formly coloured, the desired object would not be achieved,
`namely the formation of veining imitating that of standard
`natural Stone.
`0063. At the same time, as demonstrated by experimental
`tests, the coloured Zones affect the entire thickness of the
`mixture, so that the predefined object of the invention is fully
`achieved.
`0064. The variant shown in FIG. 4 proposes the alternative
`Solution of mounting on the cross-member 36 an assembly
`with just a few colouring agent dispensing devices 38, said
`assembly 38 having, connected thereto, a drive system for
`controlled displacement thereof along the cross-member 36.
`0065. It is evident that a solution midway between those
`described above is possible, namely one where a smaller
`number of dispensing devices 40 are mounted on the cross
`member 36, with the each of them designed so that it is
`movable along the cross-member over a limited distance, so
`as to ensure more correct distribution of colouring agent on
`the surface of the mixture which is transported by the upper
`surface 32 of the extractor belt 30 towards the temporary
`Support 14.
`0066. The product obtained fully satisfies the aforemen
`tioned requirements and has the appearance shown in FIGS.5
`and 6 (where it is possible to see a slab with a toroidal edge
`and a slab with a semi-toroidal edge, respectively, the Veining
`being visible throughout the thickness of the slab and there
`fore also along its edges).
`0067 Finally, it should be noted that with the present
`invention a further advantage is achieved, mainly that of
`avoiding the need for any further operation on the mixture
`already deposited on the temporary Support (for example
`using spiked tools) in order to ensure greater distribution of
`the colouring agent, with the obvious advantage in terms of
`simplification of the apparatus and the operating cycle.
`0068. It is understood that conceptually and mechanically
`equivalent modifications and variations are possible and may
`be envisaged without departing from the scope of the present
`invention as defined in the accompanying claims.
`1.-12. (canceled)
`13. A method for manufacturing slabs comprising:
`preparing at least one mixture, the mixture comprising a
`bonding agent and at least one granular product that
`comprises a stone or stone-like or ceramic material hav
`ing a specific particle size distribution;
`loading the at least one mixture into a metering/distributor
`unit that comprises a hopper and an extractor belt, the
`hopper having a top mouth for loading the mixture and a
`bottom opening for discharging the mixture, and the
`extractor belt having an upper Surface that forms a bot
`tom of the hopper;
`transferring, by means of the extractor belt, the at least one
`mixture, having been loaded, to a downstream position
`beneath a dispensing device;
`dispensing at least one coloring or pigmenting agent from
`the dispensing device onto a surface of the mixture that
`has been transferred to the downstream position, the
`dispensing resulting in a non-uniform distribution of the
`at least one coloring or pigmenting agent on the Surface
`of the mixture;
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`

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`US 2010/0194-005 A1
`
`Aug. 5, 2010
`
`further transferring, by means of the extractor belt, the
`mixture, which has the non-uniform distribution of the
`agent on the surface thereof, so that the mixture freefalls
`from the extractor belt to be distributed, in the form of a
`layer having a predetermined thickness, on a temporary
`Support;
`Subjecting the layer of mixture formed on the temporary
`Support to vibrocompression so as to obtain a rough
`formed slab; and
`transferring the rough-formed slab into a hardening sta
`tion.
`14. The method according to claim 13, wherein:
`the bonding agent of the at least one mixture comprises one
`of an inorganic material and a synthetic resin;
`the step of subjecting the layer of mixture formed on the
`temporary Support to vibrocompression is carried out by
`a press, for a predetermined period of time, while a
`vibratory movement of a pre-chosen frequency is
`applied to a ram of the press and the layer formed on the
`temporary Support is placed under a vacuum of given
`intensity and Subjected to the action of a press; and
`the hardening station Subjects the transferred rough
`formed slab to a hardening procedure that corresponds
`to the nature of the bonding agent.
`15. The method according to claim 13, further comprising:
`drying the rough-formed slab following vibrocompres
`sion; and
`high-temperature baking the rough-formed slab following
`drying:
`wherein the bonding agent comprises one of clay and
`kaolin, and one of sodium silicate and a mixture of
`silicasol with polyvinyl alcohol.
`16. The method according to claim 13, wherein dispensing
`the at least one coloring or pigmenting agent comprises dis
`pensing the at least one coloring or pigmenting agent from a
`plurality of positions that are aligned transversely with
`respect to a direction in which the extractor belt transfers the
`at least one mixture.
`17. The method according to claim 13, wherein the color
`ing or pigmenting agent comprises colored or reflective gran
`ules.
`18. An apparatus for producing slabs, the apparatus com
`prising:
`a mixture metering/distributor unit comprising a hopper
`and an extractor belt, the hopper including a top mouth
`for loading a mixture into the hopper and a bottom
`opening for discharging the loaded mixture, a portion of
`the extractor belt being positioned beneath the hopper
`and having an upper Surface that forms a bottom of the
`hopper in proximity to the bottom opening of the hopper,
`the extractor belt configured to transport a loaded mix
`
`ture downstream from the bottom opening to an end
`Zone, at which end zone the mixture freely falls from the
`extractor belt onto a temporary Support; and
`at least one coloring agent dispensing device positioned
`above the extractor belt, in proximity to the end zone, so
`as to dispense at least one coloring or pigmenting agent
`onto a Surface of the mixture that is being transported
`downstream by the extractor belt.
`19. The apparatus according to claim 18, wherein the hop
`per further includes a shaped or conveying wall that extends
`toward the bottom opening of the hopper and has a profile that
`curves towards an inside of the hopper.
`20. The apparatus according to claim 18, wherein the at
`least one coloring agent dispensing device comprises a plu
`rality of dispensing devices.
`21. The apparatus according to claim 20, wherein each of
`the plurality of dispensing devices is independently con
`trolled.
`22. The apparatus according to claim 20, wherein the plu
`rality of dispensing devices are aligned transversely with
`respect to a direction in which the extractor belt transports the
`mixture.
`23. The apparatus according to claim 20, wherein each of
`the dispensing devices includes a nozzle designed to emitajet
`of the at least one coloring or pigmenting agent, each jet
`striking a strip of the Surface of the mixture.
`24. The apparatus according to claim 18, further compris
`ing:
`a carriage, on which the mixture metering/distributor unit
`is mounted, the carriage being movable with respect to
`the temporary Support; and
`a Support structure also mounted on the carriage;
`wherein the Support structure includes a cross-member to
`which the at least one coloring agent dispensing device
`is fixed, the cross-member extending transversely with
`respect to a direction in which the extractor belt trans
`ports the mixture.
`25. The apparatus according to claim 24, wherein the at
`least one dispensing device is movable along the cross-mem
`ber in a controlled and adjustable manner.
`26. The apparatus according to claim 24, wherein the at
`least one coloring agent dispensing device comprises a plu
`rality of dispensing devices being arranged along the trans
`verse extent of the cross-member.
`27. The apparatus according to claim 26, wherein each
`dispensing device is movable along the extent of the cross
`member over a limited distance, so as to ensure more correct
`distribution of the at least one coloring or pigmenting agent
`onto the surface of the mixture that is being transported down
`stream by the extractor belt.
`
`c
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