HUE030142T2

HUE030142T2 - Recycling technology

Info

Publication number: HUE030142T2
Application number: HUE10807638A
Authority: HU
Inventors: Arthur James New
Original assignee: Mdfr Natural Fibres Ltd
Priority date: 2009-12-22
Filing date: 2010-12-22
Publication date: 2017-04-28
Also published as: EP2516730A1; EA201290561A1; WO2011077155A1; LT2516730T; ES2610204T3; BR112012015362A2; EA021142B1; RS55554B1; PT2516730T; BR112012015362B1; DK2516730T3; GB2476465A; PL2516730T3; EP2516730B1; KR20120106837A; MY154712A; GB0922364D0; KR101365923B1; SI2516730T1; HRP20170004T1

Description

Description [0009] The present invention is a method to recover the constituent wood fibres from waste and rejected en-TECHNICAL FIELD gineered wood materials, preferably in a continuous process, such that the fibre recovered is of sufficient qual- [0001] The invention relates to the recycling of engi- ity to be recycled into/reused within the fibre board man- neered wood materials such as fibre boards and particle ufacturing industry (as a substitute for virgin wood fibre) boards. More specifically, the invention relates to recov- and other end use applications including but not limited ery of the constituent wood fibres from waste engineered to insulation materials, fillers for plastic / cement corn- wood materials for re-use as a substitute for virgin wood posites, spill absorbents and horticultural growth media, fibre. This invention does not relate to pulping processes [0010] The method employs (i) the addition of water that recover fibre from lignocellulosic materials for paper with or without additives to a mass of waste composite or cardboard production. engineered wood material and (ii) the application of ohm ic (conductive) heating to that same mass. The benefit BACKGROUND of applying ohmic heating is the uniform and penetrative heating effect generated by this technique without burn- [0002] Wood based composite fibre boards and parti- ing or charring the wood fibres. The waste material is cle boards (panels) are commonly used as raw materials preferentially mechanically broken down (shredded) be- for furniture manufacture, joinery, shop fitting and con- fore heat application or water addition to aid process ef- struction. They are mass produced in many parts of the ficiency. Further mechanical disruption of the board ma- world (upwards of 22 million tonnes annually). They typ- terial is applied to the water board slurry before drying of ically comprise a matrix of refined timber fibres, wood the fibres takes place. Surface agents may be employed chips or shavings bonded together under high pressure to accelerate the impregnation of the fibre board pieces and temperature, usually with the addition of a resin or by the added water. Electrolytes maybe added to the adhesive. Most prominent of these panel types are me- water to optimise conductivity and improve heating effi- dium density fibre board (MDF) and high density fibre ciency. board (HDF). [0011] The method employs a use of high tempera- [0003] Fibre boards and particle boards are fit for pur- tures in the range of 30°C to 99°C (and preferably in the pose but do not lend themselves readily to effective re- range of 80°C to 99°C) on a slurry (mix) of water and cycling. Over 170,000 tonnes of MDF is thought to enter engineered wood material. The application of high tem- the waste stream yearly in the UK from primary and sec- perature using ohmic heating reduces the adhesive (both ondary processing activity (commercial and industrial added resin and natural lignin) bonding between the waste streams). Significantly greater amounts when post lignocellulosic elements thus allowing the constituent consumer waste is taken into account. wood fibres to be readily separated from each other.

[0004] Handling of these waste streams is made more [0012] The method preferably further employs the use problematic by the commonly employed technique of ap- of a continuous system. plying a surface finish to the board during or after man- [0013] The method may further employ the use of el- ufacture. Fixtures and fittings e.g. inserts and hinges that evated temperatures (above 100°C) in a pressurised might be applied to products manufactured from fibre ohmic heating module. board also add complexity to the identification of an ef- [0014] The method mayfurtheremploythe useof rapid fective recycling process. de-pressurisation, via a high pressure nozzle (or array [0005] There is currently no viable economic process of nozzles), as an aid to drying of the recovered fibres, to recover wood fibre from these waste streams and con- A fibre separation effect is also induced during de-pres- sequently it is disposed of eitherto landfill or incineration. surisation which aids materials handling and facilitates

This contributes to the unsustainable use of landfill and more efficient supplementary drying if required. This dry- loss of recycling potential. ing method may operate either as a result of rapid de- [0006] EP-A-1 886 586 relates to devices for ohmic pressurisation from a pressurised ohmic heating module heating of food compositions, in particular soups. or be employed as a subsequent independent pressure sub-system within a continuous process line that utilises STATEMENT OF INVENTION ohmic heating at ambient pressure.

[0015] The invention is important from a sustainable [0007] The term "slurry" is used throughout this docu- development perspective as it offers the potential for re- ment to describe material that consists of a water and ducingtheenvironmentalburdenofanimportantelement board mixture that ranges from small pieces of wet solid of the timber products supply chain whilst generating board through to individual wood fibres held in water. added value to, and prolonging the service life of, long [0008] The term "engineered wood material" is used length wood fibres. to describe material such as fibre board and particle [0016] The continuous nature of the processis a highly board that has been constituted by artificially bonding preferred factor that allows the process to be relevant to together fibres, chips or other small particles of timber. the high volume needs of the composite fibre board man- ufacturing sector, where raw material feed stock through- ing multiple entry points into the fibre board manufactur- put rates can reach upwards of 40 tonnes per hour. ing process line (which can vary between plants). Re- 10017] In addition, the method according to this inven- covered fibres can also be dried and baled for more ef- tion is capable of separating commonly found surface ficient storage and use in alternative application markets, finishes from the wood fibre element of the engineered [0021] This invention differs from the invention dis- wood product. These finishes are used during or after closed in international patent application WO 03/026859 production as a means of adding value to ’commodity’ A1, whereby waste board material is processed in a low products such as fibre board. These finishes typically in- volume batch fashion using a chemo-thermo-mechanical elude veneer, paper foil, paint or other type of ’laminate’ process. and have to be removed before the recovered wood fibre [0022] The use of ohmic heating is a highly efficient can be reused. This invention addresses that require- and cost effective means of heating in both capital and ment. Options exist to pre-treat the waste utilising me- operational cost terms. This offers an advantage over chanical methods such as sanding, high pressure water thetechnologysuggestedbyJawaid(patentGB2410746 jetting or planing. However, where these methods are B) whereby electromagnetic radiation is proposed as a not practical, flotation separation (including froth sepa- means of assisting with the degradation and recovery of ration) can be used afterthe application ofohmic heating. wood fibres from waste lignocellulosic board material.

Alternative (or additional) separation can be achieved via [0023] Operational benefits from this ohmic heating the use of air separation technologies (such as cyclonic technique would include a more controlled temperature separators) during or after drying of the fibres has taken profile and a more homogenous heating profile of the place. slurry during processing of the board and so a more pre- [0018] This invention has global application in that dictable recovery cycle with nodangerofburningorchar- composite boards are widely manufactured and used. It ring the material and reduced operational fire risk. will provide a new source of raw material for the produc- [0024] This invention incorporates an optional high tion of composite boards such as MDF, which are cur- pressure pumping unit into which the ohmic heating el- rently highly sensitive to the use of recycled timber feed ementscan be integrated. The unit may alternatively form stocks. The fibre recovered from this process will be of a discrete module after the ohmic heating has been ap- comparable ’quality’ to that of the virgin wood fibres pro- plied. The rapid release of pressure from this unit via a duced from chips or logs by the typically employed refin- high pressure nozzle array designed to permit the pas- ing process. The fibres resultantfrom this inventive proc- sage of the water and suspended wood fibre allows for ess can be applied in a flexible manner in terms of their instant evaporation ofa substantial portion of the inherent physical characteristics; length, moisture content etc can moisture contained within and between the wood fibres, be controlled. The effective manner in which this inven- A fibre separation effect is also witnessed. This drying tion allows for wood fibre to be recycled is important at effect is achieved at a relatively low energy and cost bur- thistime because it reduces the demand for virgin timber, den. Supplementary drying may also be required or de- a scarce natural resource. sirable dependent on the application for the recovered fibre.

ADVANTAGES

INTRODUCTION TO DRAWINGS

[0019] This technology allows for the recovery of wood fibres from waste engineered wood material such that [0025] Figure 1 is a schematic of the preferred process the recovered fibres remain of suitable quality for the re- for recovering wood fibre from waste fibre board, introduction into fibre board or other manufacture. This process is repeatable in that fibre board manufactured DETAILED DESCRIPTION OF PROCESS with recovered fibre content can itself be recycled when appropriate. This offers environmental and economic ad- [0026] MDF and other engineered wood material vantages over other recycling / disposal methods such waste can be categorised into two distinct types-that as composting / incineration with energy recovery, which is unfinished i.e. has no surface coating applied whereby the fibres are ’lost’ after a single cycle. (raw board) or that which is finished i.e. has a veneer, [0020] In one aspect, this invention allows for the con- foil, paint or other form of laminate applied to the surface tinuous recovery of high volumes of wood fibre from and /or edges. This invention is capable of processing waste engineered wood material thus allowing the recov- these wastes together i.e. mixed waste streams of both ered fibre to be introduced directly into the MDF manu- finished and unfinished material being treated simulta- facturing process. This is a significant advantage over neously or by diverting finished waste material via an ’batch’ processing, which would be unable to supply re- initial ’cleaning’ module where the surface finish is re covered fibre in a manner suited to manufacturing moved via mechanical means throughputs ranging from 10 tonnes - 40 tonnes per hour. [0027] Each waste recovery processing plant is likely

This invention also allows for flexibility and control of the to operate a specification for incoming waste material moisture content of the recovered fibres, therefore offer- dependent on the commercial activity within its catch- ment area e.g. cluster of furniture manufacturers or a tion into the fibre board pieces. The feed into this module major retailer’s distribution centre (where waste materi- will be controlled by a plug screw, displacement pump or als may be received after back hauling from multiple out- similar device which maintains a constant throughput, lets). The plug screw also acts as a seal to ensure that no [0028] If required, a mechanical breakdown module unwanted release occurs from the heating module which (1.1) will form the beginning of this invention with shred- may be operating under raised (above atmospheric) ding the most likely operation to be employed. The re- pressure. A high pressure displacement pump may be moval of surface finishes is best achieved by shredding employed to raise the internal pressure of this module material to a relatively uniform size, each piece having preferably to between 1.0 atmosphere and 20 atmos- approximate dimensions of 80mm x 80mm. However, pheres (to prevent boiling) dependent on the process ohmic heating is most efficient when the average size of temperature requirements. the shredded fibre board pieces is less than 20mm x [0033] The heating module will typically take the form 20mm. This allows for a more even distribution of inter- of an angled insulated cylindrical vessel between 0.2m stitial water across the ohmic heater cavity. Taking into and 20m in length with a diameter of between 50mm and account these variations, the optimum waste piece size 500mm. Based on a typical throughput rate of five tonnes parameters have been established as between 25mm x per hour of waste fibre board, these dimensions would 25mm and 45mm x 45mm. Removal of metallic or other be approximately 15m in length with a diameter of solid contaminants will be addressed immediately after 220mm. This would allow the slurry to remain in the heat- the shredder with an induction magnet (1,2a) for ferrous ing module for a period of a few minutes: typically about metal removal and an eddy current separator (1.2b) for 3 minutes depending on the operating temperature, the removal of non-ferrous contaminants (screws, nails, [0034] Electrodesaresituatedontheinsideoftheproc- fixings, hinges and other inserts that might be found in ess vessel in a shaped array of two or more electrodes part-worked or post consumer fibre board wastes). that is configured to maximise the heating and penetra- [0029] After shredding the material is graded via an tive potential of the system. The shaped array is custom- automated sieve (1.3). A mesh conveyor, which employs ised to flow rates, power requirements and conductivity a degree of vibration, will remove dust and fines. Dust of the slurry and can be controlled to optimise heater extraction (1.4) is used at this point to maintain a safe temperature for given throughputs, input temperatures working environment. and conductance of the slurry. The ohmic heater will typ- [0030] The material is then fed into a dipping tank (1.5) ically operate in the range of20KW to 1500KW. The slurry which contains hot water at a temperature above 30°C is maintained at a temperature of at least 50°C and pref- with the optimum operational range of between 80°C and erably at least 90°C while it remains in the vessel. If the 99°C. The purpose of this module is to allow the fibre vessel is pressurized, the operating temperature may be board waste to absorb sufficient volume of water so as increased up to 160°C. to allow conductive heating to operate efficiently and pre- [0035] The material may exit from the ohmic heater via dictably. The water may contain added surfactants to en- a water column or tower in order to maintain the pressure hance or accelerate the wetting of the fibre board. The within the heater. water may also contain added salts (for example NaCI [0036] After passing through the ohmic heater, the main a 0.05M solution) to enhance the conductivity of the terial may stillcontain loose ’clumps’ (clusters or bundles) resulting slurry. of un-separated fibres. The material may therefore re- [0031] The initial shredding (1.1) allows for greater sur- quire some additional agitation to reach a completely ho- face area of fibre board to be exposed to the water when mogeneous state. immersed in the dipping tank therefore reducing the time [0037] ’De-clumping’ or de-agglomeration may be required for sufficient absorption to take place. It is pref- achieved by feeding the material into a rotating cylinder erable to limit the water uptake to the minimum required that may or may not be warmed. The rotating cylinder so as to reduce the cost and energy involved in removing may also be used to selectively capture remaining pieces it again later in the process. Dependent on the mix of the of waste laminate. An airflow system may also be used waste streams being processed, moisture uptake will be that introduces physical barriers to the free passage of optimised between the higher moisture content required fibres. This will achieve the effect of liberating the indító maximise ohmic heating efficiency and the lower mois- vidual fibres from the remaining clumps at this stage, ture content to minimise the energy required to dry the [0038] The material post de-clumping is dried (1.7). processed fibres. In one example, the moisture content Following drying any remaining pieces of waste laminate of the fibre board may be increased from approximately may be removed in an air cyclone prior to baling and 8%wwb(wetweightbasis/totalweight)toapproximately packing of the recovered fibres (1.8). Alternatively, the 70% wwb. recovered fibres may be fed immediately into a further [0032] Thewaste material is then conveyed into a con- manufacturing process at the same location. tinuous feed hopper which introduces the fibre board [0039] In the case of more liquid slurries exiting the pieces to the ohmic heating module (1.6). The ohmic ohmic heater de-clumping of fibres is achieved via me- heaterwill allow for rapid and homogenous heat absorp- chanical agitation, typically by the use of an in-line ribbon blender module. Flotation separation techniques may be neered wood material is in the range 25mm to 45mm. applied to remove any residual waste laminate. This is followed by mechanical de-watering of the slurry. After 10. A method according to any preceding claim, further mechanical de-watering the material is subject to de- comprising a step of separating impurities from the clumping and drying. De-clumping or de-agglomeration slurry before or after the heating step, and subsequent processes may then be carried out as previously described. Where the liquid slurry is still under 11. A method according to any preceding claim, wherein, pressure it may be pumped into one of two (or more) after heating, the slurry is subjected to rapid depres- pressure vessels which are alternately isolated from the surization. continuous system once full. From these pressurized holding tanks the slurry is pumped through a spray nozzle 12. A method according to any preceding claim, further array where a sudden and explosive pressure release comprising transporting the slurry through a vessel occurs which ’blows apart’ the friable matrix of each in which the heating step is carried out in a continu- waste fibre board piece such that individual constituent ous process, fibres are released. The material post spraying is further dried as required. Following drying any remaining pieces of waste laminate may be removed in an air cyclone. Patentanspriiche 1. Verfahren zum Wiedergewinnen von Fasern aus ei-Claims nem kiinstlichen Holzmaterial, umfassend die

Schritte 1. A method of recovering wood fibres from engineered wood material, comprising the steps of: Vermischen von gehackseltem kiinstlichem

Holzmaterial mit Wasser zum Bilden einer mixing shredded engineered wood material with Schlámmung; und water to form a slurry; and Durchschicken von elektrischem Strom durch passing an electric current through the slurry to die Schlámmung zum Erhitzen des gehacksel- heat the shredded wood material and thereby ten Holzmaterials und dadurch Schwáchen der weaken the bonding between wood fibres in the Verbindung zwischen den Holzfasern im Holz- wood material. material. 2. A method according to claim 1, wherein the slurry is 2. Verfahren gemaB Anspruch 1, wobei die Schlarn-

heated to a temperature between 30°C and 99°C. mung auf eine Temperaturzwischen 30°C und 99°C erhitzt wird. 3. A method according to claim 2, wherein the slurry is heated to a temperature between 80°C and 99°C. 3. Verfahren gerr^ Anspruch 2, wobei die Schlám

mung auf eine Temperaturzwischen 80°C und 99°C 4. A method according to claim 1, wherein the heating erhitzt wird. is carried out above atmospheric pressure. 4. Verfahren gemaB Anspruch 1, wobei das Erhitzen 5. A method according to claim 4, wherein the heating bei einem Druck über atmosphárischem Druck aus- is carried out at a pressure between 1 and 20 átmos- geführt wird. pheres (0.1 and 2.0 MPa). 5. Verfahren gerr^ Anspruch 4, wobei das Erhitzen 6. A method according to claim 4 or claim 5, wherein bei einem Druck zwischen 1 und 20 Atmospháren the slurry is heated to a temperature between 30°C (0,1 und 2,0 MPa) ausgeführt wird. and 160°C. 6. Verfahren gerr^ Anspruch 4 Oder Anspruch 5, wo- 7. A method according to any preceding claim, wherein bei die Schlámmung auf eine Temperatur zwischen thestepofmixingtheslurryfurthercomprisesadding 30°C und 160°C erhitzt wird. an electrolyte. 7. Verfahren gerr^ irgendeinem vorhergehenden An- 8. A method according to any preceding claim, wherein spruch, wobei der Schritt des Vermischens der thestepofmixingtheslurryfurthercomprisesadding Schlámmung zudem umfasst Zusetzen eines Elek- a surface agent. trolyts. 9. A method according to any preceding claim, wherein 8. Verfahren gerr^ irgendeinem vorhergehenden An- the average size of the pieces of shredded engi- spruch, wobei der Schritt des Vermischens der

Schlámmung zudem umfasstZusetzen eines Ober- 7. Un procédé selon une quelconque revendication fláchenmittels. précédente, dans lequel l’étape de mélange de la boue comprend en outre l’ajout d’un électrolyte. 9. Verfahren gemáB irgendeinem vorhergehenden An- spruch, wobei die durchschnittliche GröBe dér Stü- 8. Un procédé selon une quelconque revendication eke geháckselten künstlichen Holzmaterials im Be- précédente, dans lequel l’étape de mélange de la reich von 25 mm bis 45 mm ist. boue comprend en outre l’ajout d’un agent de surfa ce. 10. Verfahren gerr^ irgendeinem vorhergehenden An- spruch, zudem umfassend einen Schrittdes Abtren- 9. Un procédé selon une quelconque revendication nens von Verunreinigungen aus dér Schlámmung précédente, dans lequel la taille moyenne des par- vor Oder nach dem Schritt des Erhitzens. ties de matériau á base de bois d’ingénierie déchi- queté est dans la plage de 25 mm á 45 mm. 11. Verfahren gerr^ irgendeinem vorhergehenden An- spruch, wobei, nach dem Erhitzen, die Schlámmung 10. Un procédé selon une quelconque revendication einem schnellen Druckablassen ausgesetzt wird. précédente, comprenant en outre une étape de sé- paration des impuretés de la boue avant ou aprés 12. Verfahren gerr^ irgendeinem vorhergehenden An- l’étape de chauffage. spruch, zudem umfassend Transport dér Schlámmung durch ein Gefáβ, in dem dér Schritt des Erhit- 11. Un procédé selon une quelconque revendication zens in einem kontinuierlichen Verfahren ausgeführt précédente, dans lequel aprés le chauffage, la boue wird. est soumise á une dépressurisation rapidé. 12. Un procédé selon une quelconque revendication

Revendications précédente, comprenant en outre le transport de la boue á l’intérieur d’une cuve dans lequel l’étape de 1. Un procédé de récupération des fibres de bois á par- chauffage est effectuée dans un processus continu. tir de matériau á base de bois d’ingénierie, comprenant les étapes suivantes : mélange de matériau á base de bois d’ingénierie déchiqueté aveede l’eau pourformer une boue ; et passage d’un courant électrique dans la boue pour chauffer le matériau á base de bois déchiqueté et affaiblissant ainsi la liaison entre les fibres de bois dans le matériau á base de bois. 2. Un procédé selon la revendication 1, dans lequel la boue est chauffée á une température comprise entre 30°C et 99°C. 3. Un procédé selon la revendication 2, dans lequel la boue est chauffée á une température comprise entre 80°C et 99°C. 4. Un procédé selon la revendication 1, dans lequel le chauffage est effectué au-dessus de la pression at-mosphérique. 5. Un procédé selon la revendication 4, dans lequel le chauffage est effectué á une pression comprise entre 1 et 20 atmosphéres (0,1 et 2,0 MPa). 6. Un procédé selon la revendication 4 ou la revendication 5, dans lequel le mélange est chauffé á une température entre 30°C et 160°C.

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description • EP 1886586 A [0006] · GB 2410746 B [0022] • WO 03026859 A1 [0021]

Claims

; taAHA $ ZNÖSh'ÁSt TfeeiBSÖfcÓHÍá. In order to recover fibers from artificial wood, Ms & batMm claims 1, wherein the artificial wood lined with slurry MpePs is mixed with water: and to heat the shredded wood and hence the bond between the wood fibers in the wood, it is very flowing. The method according to claim 2, wherein the slurry is heated to between 3 ° C and 99 ° C. The method of claim 1, wherein the bonding means is: i. The method according to claim 4, wherein the heating is carried out at a pressure of between 1 and 20 atmospheres (0.1 to 2.0 M Fa) ". The method of claim 6, A 4 or 5, wherein the slurry is heated to a temperature of 30 ° C to 160 ° C.

A method according to the preceding claims, wherein electrolytes are added during mixing of the slurry. f. The foregoing claims of any one of the preceding claims:. ®t $ letchtmallmtmtmd ^ t added. A method according to any one of the preceding claims, wherein the pieces of chopped artificial wood have an average size of between 25 mm and 45 mm. 10 A method according to any of the claims, wherein prior to or after heating, the slurry is separated from the slurry © 1. II. The three-step process of the preceding claims, wherein, upon heating, the slurry is subjected to rapid pressure reduction,

The method according to any one of the preceding claims, wherein the slurry is passed through a vessel for carrying out the heating in a continuous process.