EP0077530A1 - Procédé et dispositif pour le broyage sélectif d'un matériau composite et application à l'écorçage des plaquettes de bois - Google Patents

Procédé et dispositif pour le broyage sélectif d'un matériau composite et application à l'écorçage des plaquettes de bois Download PDF

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Publication number
EP0077530A1
EP0077530A1 EP82109504A EP82109504A EP0077530A1 EP 0077530 A1 EP0077530 A1 EP 0077530A1 EP 82109504 A EP82109504 A EP 82109504A EP 82109504 A EP82109504 A EP 82109504A EP 0077530 A1 EP0077530 A1 EP 0077530A1
Authority
EP
European Patent Office
Prior art keywords
tools
grinding
elastomer
cylinder
ground
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82109504A
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German (de)
English (en)
French (fr)
Inventor
Pierre Lejeune
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alsthom Atlantique SA
Original Assignee
Alsthom Atlantique SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alsthom Atlantique SA filed Critical Alsthom Atlantique SA
Publication of EP0077530A1 publication Critical patent/EP0077530A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18—Details
    • B02C17/20—Disintegrating members

Definitions

  • the present invention relates to a method and to a device for the selective grinding of a composite material and to their application to debarking of wood chips.
  • the wood factories of the cellulose factories are currently supplied from medium-sized logs (hardwood and softwood), and from previously debarked sawmill waste (around 20% of the raw material).
  • the bark and other debris could be used as fuel, either directly or as a source of methane or methanol.
  • the best suited dry grinding methods are those which involve shock phenomena such that the chip is placed, as well as its bark, as between "hammer” and “anvil”, with constraints successive compression and decompression such that the bark peels off the wood, at the same time as it breaks.
  • the grinding is sufficiently selective so that, under the effect of the shocks, the bark is broken into small particles, easily separable by sorting on a sieve, without however breaking the wood.
  • the main difficulty for the application of these processes is that: if the bark generally has a higher breaking strength weak than that of wood, and this because it is less rich in cellulose, it is also generally more flexible and more compressible; so that the energy required to break the bark is often very similar, and sometimes even greater, than that which causes the wood to break. Under these conditions we can imagine that if the energy received by the wood, in the impact impact zone, is, per unit of area, the same size as that received by the bark, the wood can break almost as quickly , or sometimes even faster than the bark.
  • the object of the present invention which is applicable to debarking of wood chips, is to provide a solution to the selective grinding of composite materials.
  • An object of the present invention is to improve the previous device by an appropriate choice of the characteristics of the balls and their instructions for use, so as to obtain maximum efficiency.
  • the subject of the invention is therefore a process for grinding a material in the form of an agglomerate having at least two constituents of different hardness, making it possible to selectively grind at least one of the constituents while providing at least one another constituent by hammering the material by means of grinding tools of spherical shape arranged in a grinder, said tools being deformable and consisting of a core coated with an elastomer, characterized in that for a shock of the same total energy, l energy involved in the deformation of the tool is greater than that absorbed by the material to be cleaned, during an impact on the material to be cleaned, and less than that absorbed by the material to be ground, during an impact on the material to be ground.
  • the invention also relates to a device for grinding a material in the form of an agglomerate having at least two constituents of different hardness, said grinding grinding at least one of the constituents and providing at least one other constituent, comprising a rotary cylinder (1), rotating about a substantially horizontal axis, means (6) for introducing the material (4) into the cylinder, means (28A, 28B, 29A, 29B, 30, 23, 24) for introducing hammer tools (15) acting as hammer into the cylinder, the internal wall of the cylinder acting as an anvil, the selective grinding being effected by the action of repeated shocks generated by the fall of the tools rotation of the cylinder, means for separating (21) and evacuating (26, 29) the grinding products, the hammering tools (15) comprising a ballasting core (16A, 16B) and an elastomer coating (17A, 17B), in the form of concentric spheres, characterized in that the weight P of s tools, the diameter D of the cylinder, the radius of cur
  • the reference 1 designates a hollow metal cylinder, open at both ends, of substantially horizontal axis, driven in rotation about its axis.
  • the means for rotating the first cylinder advantageously consists, in a known manner, of bridges of the construction machine type comprising wheels 2 associated with drive motors such as 3.
  • the wheels are in contact with treads 5 with which the outer periphery of cylinder 1 is provided.
  • the strips of wood to be debarked are brought to a first end of the cylinder (on the left in FIG. 1) by means of a movable belt 6.
  • the cylinder 1 is provided with orifices such as slots for sifting the wood during debarking. (But these holes are optional, in their absence, sorting is done independently of the device).
  • the fines passing through the sieve are evacuated by a mat 9 placed under the cylinder 1.
  • the entire cylinder 1 is surrounded by a casing 10 visible in FIG. 2 which makes it possible to collect and collect the sieving products.
  • the dimensions of the cylinder are, for example, 3.50 m inside diameter and 8 to 9 meters in length.
  • the cylinder also receives a constant supply of organs or grinding tools 15 proportional to the flow rate of the plates, and constituted by deformable elastic spheres, formed by a dense 16 A ballast core, coated with a layer of elastomer 17 A (FIG. 3A).
  • the platelets to be treated most often have an average size of around 30 x 20 x 5mm, but they can occasionally be larger. larger or smaller, and spread around this average dimension.
  • the tools 15, preferably spherical in shape have a diameter close to 60mm, that is to say greater than the largest mean dimension of the inserts. It will therefore be easy, to recover them, to separate them from the plates by dimensional sorting.
  • the drum has a relatively high speed of rotation, of the order of 20 revolutions / minute, so that the centrifugal force presses the tools and the inserts against the interior wall, and helps them to go up, in the form of 'an embankment, in the direction of rotation, under the effect of friction forces. Elements fixed against the interior wall of the drum can possibly facilitate lifting.
  • the filling rate of the drum in the case of the example cited, is of the order of 25%.
  • the mass of tools, of substantially spherical shape, and the quality and thickness of the elastomer which coats the ballasting core are chosen according to the nature of the wood to be treated: hardwood or softwood, hard or soft wood, wood green or dry wood, etc,
  • the energy involved in the shock phenomena must be sufficient to exceed the limit of elastic deformations of bark and cause it to break.
  • the tool should deform sufficiently, upon impact on the wood, so that the stress exerted 'does not exceed the elastic limit of wood.
  • the elastomer that the tool covers will ultimately appear to be more flexible than wood and less flexible than bark, the coefficient of elasticity chosen obviously being a function of the thickness of the elastomer layer.
  • the inner wall of the drum is itself coated with a layer of elastomer.
  • the material constituting the drum or its lining or internal shielding resist the attack of the organic acids secreted by the vegetable materials, and this in order to avoid both an attack of the drum and a possible coloring of the platelets with metallic salts.
  • good abrasion resistance is sought, due to the frequent presence of silica in batches of platelets.
  • the drum can be provided with lights of sufficiently small size so that the plates are retained inside the drum.
  • a casing surrounds the drum to collect fines and dust, and, suitable devices such as conveyor belt, ventilation circuit and cyclone separator, make it possible to evacuate this waste which it may be advantageous to burn.
  • the average residence time required for treatment will depend on the nature of the wood. For example, for maritime pine edgings, and, with the tools defined above, this treatment time would be of the order of 30 minutes for a debarking rate close to 90%.
  • the treated materials are retained up to a certain level using a movable threshold 20 of adjustable height which makes it possible to adjust the filling rate.
  • the tools are stored in storage hoppers 28A, 28B.
  • a switch 30 located on the coarse material recycling circuit allows to direct the tools to the storage hopper assigned to them.
  • the supply of tools to the installation is done by the base of the hoppers by conduits 29A, 298.
  • the face of the tool which presents itself upon impact retains a spherical shape, but it is possible to obtain a greater transfer of energy per unit of surface struck.
  • the invention which has been described with reference to an installation for debarking wood chips, makes it possible to solve other problems of selective grinding.
  • the energy absorbed per unit area of the material to be housed is less than that absorbed per unit area of the material to be ground.
  • the total energy involved in the individual shocks and related to the impact surface of the shock, as well as the deformability of the "hammer” and or of the “anvil”, are chosen so that the specific energy transmitted to the material to be housed in the impact zone remains below the specific energy of rupture of this material, and preferably maintain this material within the range of elastic deformations; while the specific energy transmitted to the material to be ground in the impact zone on this material is beyond the specific detachment or rupture energy of this material, i.e. beyond the range of elastic deformations relating to this material.
  • a preferential condition for the application of the method is to choose the nature of the materials constituting the "hammer” and or “anvil” in such a way that their deformations, upon impact, do not exceed by the limit of the elastic deformations proper to these materials, and, that the "hammer” and / or “the anvil” therefore regains, after the impact, substantially its initial shape.
  • Another preferential condition is to choose the tools and the materials so that the thermal energy dissipated within the "hammer” and / or the “anvil", in the deformations which accompany the shocks can be evacuated properly without causing an excessive rise in temperature.
  • a third preferential condition for applying the method independent of the previous two is that the shape and size of the "hammer" are such that the surface of the impact zone is at most of the same order of magnitude as the size of the most small parts to spare, so as not to exceed excessive forces on these small parts.
  • a fourth preferential, non-essential and non-limiting condition for the application of the method is that the "hammer" is of substantially spherical shape, or that it always appears, in front of the impact, in the form of a portion deformable sphere, in which case, its deformation being greater upon impact on the material to be housed than on the material to be ground, the surface area of distribution of forces is greater with respect to the material to be housed than with vis-à-vis the material to be ground which further reduces the stresses on the material to be housed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Pulverization Processes (AREA)
  • Debarking, Splitting, And Disintegration Of Timber (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
EP82109504A 1981-10-19 1982-10-14 Procédé et dispositif pour le broyage sélectif d'un matériau composite et application à l'écorçage des plaquettes de bois Withdrawn EP0077530A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8119577 1981-10-19
FR8119577A FR2514667A1 (fr) 1981-10-19 1981-10-19 Procede et dispositif pour le broyage selectif d'un materiau composite et application a l'ecorcage des plaquettes de bois

Publications (1)

Publication Number Publication Date
EP0077530A1 true EP0077530A1 (fr) 1983-04-27

Family

ID=9263152

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82109504A Withdrawn EP0077530A1 (fr) 1981-10-19 1982-10-14 Procédé et dispositif pour le broyage sélectif d'un matériau composite et application à l'écorçage des plaquettes de bois

Country Status (8)

Country Link
EP (1) EP0077530A1 (no)
CA (1) CA1177042A (no)
ES (1) ES516652A0 (no)
FI (1) FI823524L (no)
FR (1) FR2514667A1 (no)
GR (1) GR77722B (no)
NO (1) NO823437L (no)
PT (1) PT75695B (no)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10063798A1 (de) * 2000-12-21 2002-06-27 Kloeckner Humboldt Wedag Kreislaufmahleinrichtung mit Hochdruck-Walzenmühle und Sichter

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1807383A (en) * 1928-09-29 1931-05-26 Rubber Surfacers Inc Grinding method and apparatus
FR836189A (fr) * 1937-06-04 1939-01-12 Perfectionnements aux appareils broyeurs et délayeurs et au traitement de matièresminérales brutes dans ces appareils
DE1071451B (no) * 1959-12-17
GB1159259A (en) * 1966-12-08 1969-07-23 Smidth & Co As F L Method of and Mills for Grinding Mineral Materials
GB1216191A (en) * 1967-01-05 1970-12-16 Foster Wheeler Brown Boilers Improvements in and relating to pulverising mills

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1302644A (fr) * 1961-07-21 1962-08-31 Loire Atel Forges Boulets pour broyage de matériaux divers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1071451B (no) * 1959-12-17
US1807383A (en) * 1928-09-29 1931-05-26 Rubber Surfacers Inc Grinding method and apparatus
FR836189A (fr) * 1937-06-04 1939-01-12 Perfectionnements aux appareils broyeurs et délayeurs et au traitement de matièresminérales brutes dans ces appareils
GB1159259A (en) * 1966-12-08 1969-07-23 Smidth & Co As F L Method of and Mills for Grinding Mineral Materials
GB1216191A (en) * 1967-01-05 1970-12-16 Foster Wheeler Brown Boilers Improvements in and relating to pulverising mills

Also Published As

Publication number Publication date
PT75695B (fr) 1985-11-13
FI823524A0 (fi) 1982-10-15
FR2514667A1 (fr) 1983-04-22
ES8306965A1 (es) 1983-06-16
CA1177042A (fr) 1984-10-30
GR77722B (no) 1984-09-25
FI823524L (fi) 1983-04-20
ES516652A0 (es) 1983-06-16
NO823437L (no) 1983-04-20
PT75695A (fr) 1982-11-01

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Inventor name: LEJEUNE, PIERRE