Classifying – separating – and assorting solids – Sifting – Special applications
Patent
1979-09-17
1982-06-29
Hill, Ralph J.
Classifying, separating, and assorting solids
Sifting
Special applications
209250, 209273, D21F 100, B07B 100
Patent
active
043371507
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a fiber fractionating device which is intended preferably as a testing device for the determination of the content of coarse particles such as chips or the like in wood fiber materials. This concerns a device which consists of
an essentially cylindrical water storage tank open at the top, having an overflow edge, an overflow channel surrounding said overflow edge with an outlet and a closable drain orifice that connects the water storage tank with the overflow channel and the outflow, respectively,
an interchangeable fractionating bottom, which is designed as a slotted plate, sieve or the like and rests inside the water storage tank on a support above the bottom of the water storage tank that is essentially annular and provided with communicating water passage orifices,
a cylindrical fractionating vessel which, by means of detachable fastenings is put sealingly on the edge of the fractionating bottom and is tightened against the annular support,
a flexible membrane which is clamped into an opening in the bottom of the water storage tank within the annular support and has a rigid center piece that is provided on its bottom side with a periodically pulsatable lift drive, as well as
a controllable water feed having water outlet nozzles within the fractionating vessel.
STATE OF TECHNIQUE
The fiber materials, which are obtained especially from wood, for the industry producing paper, pasteboard, cardboard and related products, consist generally of a mixture of fibers having different lengths that have a certain fiber length distribution and, beyond that, contain frequently coarse components of the initial raw material, which have not yet been sufficiently broken up, as well as other possible impurifications. For the supervision of the manufacturing process it is necessary in many cases to know the content of undesirable coarse components and impurifications in a fiber material but possibly also its fiber length distribution. In order to determine these characteristics, so-called fractionating devices are used as test apparatus. The test apparatus known for this purpose use differently graduated slotted plates and sieves by means of which a sample of the fiber material distributed in a watery suspension is separated each time into a sieve passing substance and a sieve residue.
The mechanical wood pulps and wood materials obtained from the wood by means of mechanical break-up methods contain, besides fibrous cells of the wood separated by the break-up process, also cohesive fiber groups, so-called chips which, for instance, are of extreme disadvantage in paper production and for the properties of the paper. Since these chips must be eliminated and repulped the determination of the chip content of mechanical wood pulp and wood materials is of special importance especially for the production of printing papers. On the other hand, the determination of the chip content by means of fractionating laboratory apparatus offers special difficulties in contrast to a length fractionation of the more elastic individual fibers for which partly the same devices are used.
Since the length-related fractionating of fiber material suspensions has been satisfactorily solved to a considerable degree by laboratory means, the present invention relates mainly to the development of a fractionating laboratory device which is supposed to furnish satisfactory results for the determination of the chip content of wood pulp suspensions. By the interchange of appropriate sieves it is then mostly possible to use the same device successfully also for the length-related fiber fractionation.
Since for the determination of the chip content the thickness of the chips is more important than their length, sieves as they are used for length-related fiber fractionating are generally not used for the determination of the chip content but rather slotted plates which are made as precise as possible and whose slot width determines the smallest diameter of the chips to be separated.
The well-known fiber fractionatin
REFERENCES:
patent: 2734631 (1956-02-01), Kobliska
patent: 2988223 (1961-06-01), Janson
patent: 3789978 (1974-02-01), Janson
patent: 3827567 (1974-08-01), Rundqvist
"Clark Pulp Classifier", Catalog No. 218-1.
"Fiber Fractionation of Mechanical Pulp in the McNett Apparatus", Scan Test M6:69, Svensk Papperstidning, 72, (1969), pp. 312-314.
"Merkblatt VI/1/66", DAS Papier, 20, (1966), pp. 256-265.
Haindl Papier GmbH
Hill Ralph J.
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