US1717266A - Process of producing wood pulp - Google Patents

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June 1 1, 1929. SCHQUTEN 1,717,266

PROCESS OF PRODUC-ING WOOD PULP Filed March 2, 1927 l I H m P llg m "W" "I I v I I nvenlonv 7141s zl'lbrne q. f

. Patented June 11, 1929.

UNITED STATES 1,717,266 PATENT OFFICE.

FRANS KAREL LOUIS SCHOUTEN, OF ZAANDAM, NETHERLANDS.

PROCESS OF PRODUCING WOOD PULP.

Application filed March 2, 1927, Serial No. 172,045, and in Germany March 5, 1926.

The invention relates to the manufacture of I wood pulp from logs or from wood Waste, its

object being to produce, by a mechanical process, pulp approximating in quality to hot ground.

According to my process the comminuted raw material, with its natural content of moisture, or moistened to restore the normal moisture content, is first subjected to so-called dry refining, and is then subjected to further refining (wet refining) in the presence of an appropriate proportion of added water.

-This process has the advantage of producing the operation being continued till as far as convenient or practicable even the smallest bundles are divided into separate fibres. This may be done in three stages, to wit First stage.The raw material, holding its natural moisture content, is cut up or otherwise comminuted. 3'0

Second stage.-The coniminuted material, still holding itsnatural moisture content, is subjected to dry refining.

Third stage.-In order finally to separate the fibres the material is subjected to Wet refining, in the form of a thick pulp.

Logs, boards,.wood-shaving and so on may all be used as raw materials.

Such material may for the purposes of the process first be cut up into small slabs or wafers, which are then divided longitudinally of the fibres, the broken fibres and sawdust being separated, which may be done by any method usually adopted for that purpose, for example in ElfjSCIGGII. 'Thereupon the fine woodflour, sawdust, sand and other impurities may be removed by sifting. Thereupon follows the already mentioned first refining process, namely a dry process, in which the wood holds only its natural moisture content,

ture may be introduced to restore the normal content, so that the mechanical treatment in the so-called dry refining process does not unduly tear the fibres.

The dry refining preceding the wet refining has the efiect of dividing up the wood into bundles of fibres of fairly uniform size.

It is desirable for the purposes of the invention artificially to increase the heat produced by friction in the course of the dry refining process. For this purpose we may, for example, subject the beaters or coacting members of the refining apparatus to the action of springs or weights whereby their surfaces are pressed towards each other. The heat due to the resulting increased friction generates vapour in the Wood, which opens up the cells. When the wood cells, thus loosened, are placed in the apparatus for wet refining, which imparts to the material the general characteristics of hot ground, the treatment produces a pulp'capable of being inade into paper with very closely felted fibre ayers.

The treatment in the Wet refiner disintegrates practically all the wood, even the smallest portions introduced into that apparatus, so that even these small bundles of fibres are opened up and converted into a loose fibrous state, as in hot ground. For this purpose the material on its way from the dry refiner to the wet refiner must be made into a pulp of such stiffness that its temperature is increased by friction in the wet refiner.

This pulp may be produced in a vat, which is interposed between the'dry and wet refiners, and from which the pulp is conveyed to the wet refiner by means of a suitable conveyor.

The thick pulp leaving the wet refiner may receive an addition of water, and then pass on to a sorting apparatus, wherein such bundles of fibres as have not been fully disintegrated or shredded are separated, in order to pass back to the vat and be mixed with the fresh material coming from the dry refiner. This prevents or reduces the occurrence of waste in the final stage of the process. The amount of water added to the material coming from the dry refiner is, of course, regulated with due regard to the water brought with the pulp which is returned to the'vat after passing through the wet refiner and sorter. The water flowing from the sorting apparatus may, in fact, be used for regulating the consistency of the pulp which is sup plied to the wet refiner.

are further divided. From the machines 2,

the material passes to a sifting machine 3, wherein broken fibres and like waste material, sand and other impurities are separated. This treatment completes the first stage.

For the second stage of the process the material passes into the dry refiner 6, where the pieces of wood are divided up into coarse bundles of fibres, by being split longitudinally, heat being artificially generated by* friction during this treatment.

If the material coming from the sifter is too dry for this treatment it is first conveyed from the sifter to a chamber 5, wherein it is treated with water from a container 4, to restore the natural moisture content of the wood, whereupon it passes into the dry refiner 6, in which the second stage of the process is completed.

For the third stage the small bundles or bunches of fibre produced in the dry refiner 6 are passed to vat 7, in order to convert into a pulp of the consistency suitable for wet refining. A pump 8 or equivalent apparatus delivers this pulp to the wet refiner 9, in which the treatment, in so far as is practicable, is accompanied by artificial generation of heat by friction.

The fpulp from the wet refiner, with addition 0 an appropriate quantity of water, passes to the sorting or straining apparatus 10, where any coarse material left in the pulp is separated. The strained pulp passes on to the drier 11, and the water containing the Presses, centrifugal apparatus or the like I may be used for further separation of water from the pulp, and putting it into packet form. A press for this purpose is shown at 12. From such a press the material can be taken in a form ready for the market, with a moisture content of only 50 to 55%.

Alternatively the pulp coming from the sorter or strainer can be thickened to the consistency suitable for treatment in a beater, and used for paper making, the treatment in the drier 11 and press 12 being dispensed with.

l/Vhat I claim is:

The process of mechanically producing wood pulp comprising mechanically cominuting the raw material, dry refining it with suflicient friction to vaporize its normal water content, and wet refining it in mixture with In testimony whereof I have aflixed my signature.

FRANS KAREL LOUIS SCHOUTEN.

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