Classifying – separating – and assorting solids – Precedent preparation of items or materials to facilitate...
Reexamination Certificate
1999-08-30
2001-03-27
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Precedent preparation of items or materials to facilitate...
C209S004000, C209S007000, C209S009000, C209S011000, C209S017000, C209S270000, C209S284000, C209S285000, C209S288000, C209S293000, C209S294000, C209S296000, C209S297000
Reexamination Certificate
active
06206199
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a method of recovering the various components of multiple layer materials, such as materials that consist of paper, plastic and aluminium foil, and more specifically to a method applicable to a refiner or disperser having mutually opposing discs that rotate relative to one another and that have material engaging surfaces or material engaging elements.
The invention also relates to a plant for recovering such components.
Handling of material, e.g. multiple layer material, for recycling purposes entails comparatively high costs in transporting the material to a recovery plant. For this reason it is unrealistic to expect that the actual recovery plant can have a very large capacity. This would mean that the capital cost of the actual recovery plant would be so high as to cause a large recovery area with correspondingly high transport costs from peripheral parts thereof to exceed the processing value of the product obtained in the recovery plant. This recovered product shall subsequently constitute one of several different starting materials for subsequent manufacturing processes or refinement processes.
Consequently a plurality of recovery plants that have somewhat limited capacity and that serve a not unduly large recovery area can therefore be expected to show the highest returns from an economic aspect.
BACKGROUND OF THE INVENTION
Recovery of the components of multiple layer materials, for instance recovery of paper, plastic and aluminium foil from beverage packaging materials, has earlier been achieved with the aid of large drum pulpers or traditional pulpers, to which chemicals are normally added. Such large plants incur heavy investment costs, require large construction and installation areas, and consume large amounts of energy, which explains why such plants have not been used more widely.
SE,B,417 623 (Escher Wyss) discloses a method in which particles processed in a disperser are rolled to form small compact grains. The known method requires comprehensive treatment of the material upstream of the disperser and is therefore expensive and highly energy consuming.
SE,B,383 006 (Munksjö) described a method of recovering fibers from waste paper with the aid of a rotatable perforated drum provided with lifting means. The document is not concerned with layer separation of waste material.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a method and processing plant of the aforedescribed kind which will enable the components of multiple layer materials to be separated effectively without consuming large quantities of energy, and which will enable said components to be handled and recovered for further processing in a comparatively simple manner.
Another object of the invention is to provide a method and processing plant of the aforesaid kind that will enable the components of multiple layer materials to be also recovered economically in plants of comparatively limited capacity.
SUMMARY OF THE INVENTION
These and other objects are fulfilled with an inventive method.
The invention is based on the discovery that the components of multiple layer material can be separated effectively by subjecting adjacent layers to shear forces that loosen the various layers from one another without needing to subject the layers to any substantial degree of disintegration in conjunction with the layer-shearing or layer-separating operation.
Thus, there are obtained pieces or fragments of the various components that may have a more or less regular shape or a totally irregular shape.
The size of the layers of material loosened by friction may thus be in the order of an A4-size or smaller.
It is often of value to recover primarily paper from multiple layer material. However, application of the inventive method will also make the recovery of other components of the material, such as aluminium and plastic for instance, also economically justifiable.
Recovery of the paper present in such materials can be facilitated by slushing or defibering the paper to some extent in conjunction with or in connection with releasing or loosening the layers in said material. This paper slushing or suspending process can be continued and amplified in a following treatment stage.
Separation of the layers by shearing action can be made effective by using discs of different constructions in accordance with the nature of the starting material concerned, said discs being arranged to rotate relative to one another.
In some cases it is sufficient for the discs to have comparatively smooth or planar surfaces, wherewith the friction to which the material is subjected when in engagement with the discs is sufficient to produce the shearing effect desired.
In other cases, different types of engagement elements, such as teeth, bars, grooves, serrations or like elements, are required on one or both discs in order to ensure that the intended layer separation effect is achieved.
One significant factor that determines which disc construction shall be used is the thickness of the multiple layer material and the width of the gap between the discs. The width of the gap can be varied, for instance so as to decrease radially and thus have the smallest value in the peripheral region of the discs.
The state of the material supplied is also significant to the result of the layer shearing or layer separating operation.
The properties of a multiple layer material that has been moistened upstream of the infeed zone of the refiner or in said infeed zone and/or that has been heated, for instance with steam, will be different to material that is supplied to the infeed zone in a dry state. Those parameters that have an effect on the result of the operation in conjunction with the actual layer shearing operation include the construction of the disc surfaces or of the disc-carried material engaging elements, the size of the gap width, the speed at which the discs rotate, the amount of dilution liquid or suspension liquid supplied, and so on.
Upon completion of the layer separating or layer shearing operation, the various layers are pumped together with the dilution liquid added to the process optionally to a collecting vessel which may, in certain cases, be suitable in order to equalize variations in flow from the refiner.
The provision of such a collecting vessel will not be necessary in certain cases, and the separated pieces of material present in the dilution liquid can be pumped directly to a separator in which readily suspended or slushed material layers in the suspension liquid are removed separately from material layers that are not readily slushed.
Pumping of separated material layers taken-up in the suspension liquid is suitably effected against a generated counter-pressure. Trials have shown that the use of a valve or valves in order to generate this counterpressure is impractical, because of the risk of the valve or valves becoming clogged by the separated pieces of material. Instead, the counter-pressure is suitably generated by taking-up the pieces of material and the suspension liquid in a conduit, suitably a U-shaped conduit, which is extended to a given level above the refiner acting as a pump.
The final separation stage is effected by delivering the separated pieces of material present in the suspension liquid—optionally via a collecting vessel of the aforesaid kind—in the form of a pulp suspension to a generally horizontal, rotating, perforated drum that includes an internal screw feeder. Additional suspension or dilution liquid is supplied to the drum, preferably sprayed thereinto from the upper part of the drum. Those layers of material that are able to pass into suspension, e.g. relatively finely-divided pieces of paper, are able to depart through the perforations, whereas those material layers that cannot readily pass into suspension, such as pieces of aluminium and plastic, are fed out of the drum at one end by the screw feeder. Suitably constructed vessels for receiving the different materials and the suspension liquid are suitably provided beneath the d
Betz Günter
Kurtz Rudolf
Cellwood Machinery AB
Jones David
Sughrue Mion Zinn Macpeak & Seas, PLLC
Walsh Donald P.
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