US2374046A - Method of disintegrating cellulosecontaining structures - Google Patents

Description

April 1945. M. J. STACOM f 2,374,046

METHOD OF DISINTEGRATING CELLULOSE-CONTAINING STRUCTURES Filed April 25, 1940 I 5 Sheets-Sheet 2 HAMMER MILL 45 m1 FAN:

BFAE/NGS .S/L/E/VTLY /9 MOUNTED INVENTOR Matthew J. Sl'acpm ATTORNEY April 17, 1945.

M. J. STACOM METHOD OF DISINTEGRA'IING CELLULdSE-CONTAINING STRUCTURES I Filed April 25, 1940 ca l y 3 kn u a I mix Run .6: P 9 \ak 4 ,H c Y ,1 .1,

Matthew-. Etacnm ATTORNEY 5 Sheets-sheaf 4 v April 17, 1945. M. J. STACOM 2,374,045

METHOD OF DISINTEGRATING CELLULOSE-CONTAINING STRUCTURES Filed April 25, 1940 5 Sheets-Sheet 5 Work R111 Wurk R01] M atthaw Etacnm INV NTOR Patented Apr. 17, 1945 UNITED STATES PATENT: orl-lcc METHOD OF DISINTEGRATING CELLULOSE- CONTAINING STRUCTURES Matthew J; Stacom, Flushing, N. Y., assignor to 'Stacom Process Corporation, Long Island City, N. Y., a corporation of New York Application April 25, 1940, Serial No. ss 1,51 1 5 Claims. (-01. 241-2) This application is a continuation-in-part of my copending application Serial No. 98,208, filed August 26, 1936, and of my copendlng application Serial No. 195,776, filed March 14, 1938, this application being particularly concerned with a combination of the pressure step, described and claimed in the latter application, with a pulverizing step, whereby an improved disintegration of the material being treated may be obtained.

The invention herein disclosed has resulted from my. discovery that if the fibrous cellulosecontaining structures occurring in nature, such as the cellulose-bearing fibres of wood, be subjected to mechanical pressures hitherto not obtainable practically, while containing their native sap or other fluids, or after having been soaked in water if originally found in a dry condition,

the immediate products of such pressure treatment appear as relatively dry, friable masses of fibres having such slight coherence that they can be easily and rapidly comminuted by impact pulverizers, while maintained in air suspension, to a degree of fineness heretofore possible of accomplishment only by prolonged mechanical treatment with prohibitively high consumption of power in existing grinding, shredding, cutting and beating machines, when the latter are alone used on such raw materials. The products of my improved process may be used in the arts immediately after production, or after being subjected to subsequent chemical treatment such as is now employed in making paper, rayon, Cellophane and similar commercial cellulose products, but with much less time and expense because of the uniform pulverization of my products.

The invention may be utilized in passing strips of wood, about a quarter of an inch thick, longitudinally of their fibre structures through a roll mill, such as is illustrated in Figures 1, 2 and 3 of the drawings in Patent No. 2,196,651, which may be modified by the substitution of fiat sideplates for the grooved side plates shown in Figures 1 to 3. v In such apparatus it is possible with a slight consumption of power to' apply pressures,

of upward of ten tons per linear inch of contacting roll faces, to such strips of wood and I found that when this was done the product issued from the pressure zone in the form of highly friable masses which fell into small pieces when handled.

strips which were first soaked in water, and this without unfavorably aifecting the quality of the product.

Two causes contribute to this result, as I. believe, as follows: .Not only was the wet wood more easily crushed and broken by the mill, but the great pressure of many tons per transverse linear inch applied thereto in a narrow compression zone effectively expelled thecontainedjiquids from the cells or pore walls between the fibres of the wood so quickly as to burst said cells. This substantially complete expulsion from the material being pressed, during the first step of my process, of all gummy constituents including resins and the like fibre cementing elements,

is essential to the successful operation of the second step of said process when fine screens are used, because otherwise any gummy residues present in or between the cellulose fibres when fed to the hammer mill become softened by the heat generated by the operation thereof so that they soon clog any fine screen openings. This difiiculty has heretofore prevented the commercial use of such hammer mills operating on wood fibres and forcing them through screens having meshes numbering more than fifty to the linear inch in the last step in the production of wood This explanation was supported by the fact supports the conclusion that the original 'fiuid' containing cells of the wood have been burst.

This removal of the major portion of the liquid in a single application of the pressure is of importance .in the combination with the pulverizing step, since the liquid in the cells and pore walls serves as a cushion to prevent the collapse of those cells and pore-walla. Also, it serves as a medium for bursting the cells and pore walls from within, thus forming a more porous product, and as a medium for carrying away the heat units developed in thepressure zone and thus avoiding overheating of the cellulosic material. This liquid also serves as a means of carrying away the gums and tars in the wood that otherwise would interfere with the pulverizing and screening operations, particularly if overheated. As a result, the product is ina condition such that the pulverizing and screening may be expeditiou'sly accomplished.

Another feature of importance in the preferred use of the invention is th provision of a roller normally in contact with the ring and pressed toward it with great but yielding pressure. With such an arrangement the pressure applied is efiective throughout the piece being treated to prevent accumulation or concentration of the liquids in the interior of the strip of material, thus avoiding the retention of gums, etc., or a lack of uniformity that would be detrimental in the subsequent pulverizing and screening steps.

Other features of importance to the subsequent pulverizing step in the preferred operations are to have the pressure applied as the material travels in a curvilinear path and while the ring is depressed to advance the horn angle in the direction of rotation of the ring to a point where the apex is above the line of the direction of pressure of the roll against the ring.

As indicated above, the above described results of my method of operation have also been advantageously applied to wood in green condition in which the sap and other contained liquids take the place of the water of imbibition. Special success is obtained with thin strips of green pine wood grown in the Southern States which contains too much sap and resin to be useful as a source of mechanical pulp for paper making, or in the manufacture of viscose, or rayon.

The main reason why such southern pine wood, and others growing in South America, have not heretofore been used more in the cellulose industries is that their large content of gap, resin, etc., has interfered with the necessary chemical treatment and thereby rendered the standard processes too costly when applied thereto, even if an ultimately satisfactory pulp could be obtained therefrom. Hence, the industry has been restricted up to the present to the use of spruce, poplar, and fir trees as its raw material for newsprint and the fine arts.

Also, I find that the dark colored liquid expelled from these strips of green pine wood separates by gravity into two layers when allowed to stand, the upper layer containing turpentine and lighter fractions of the sap, while the larger, lower layer soon settles out a gummy resinous mass, evidently containing the pitch and resin present i the original wood. In some cases a gray-colored fluid is obtained which, upon heating to 65 or 70 C. separates as a fatty acid layer at the top and a bottom layer containing carbohydrates and other matter. Consequently such excess of sap not only serves a useful purpose in my :process, but also forms valuable lay-products at the same time.

I have also found that green cornstalks can be used as raw materials in the process of my invention with apparently the same success as that obtained with soft green southern pine, such stalks (preferably those which have been grown for fodder) being run preferably lengthwise through the mill in full length. Large volumes of colored liquid are then expressed, while the fibrous sheath and the pith of such stalks come through as thin, dry, friable masses which are easily pulverized in a hammer mill to a. degree which promises to render them usable in the manufacture of paper and other cellulose products.

Application of my process to sugar cane offers promise of equally great improvements over results now obtained in the sugar industry by passing the cane through numerous sets of rolls journaled in fixed bearings in the sugar mill and adjusted so as to produce progressively reduced roll passes. This process as now in use leaves a large portion of the sugar juice or molasses in the bagasse which is still too damp to be easily burned as fuel. The method of my invention would also burst most of the 25% of the cellulose cells of the cane now left in the bagasse and thus produce more nearly sugar extraction, while reducing the dried-out cane fibre to such a fine degree of comminution that it can be used as fuel in pulverized fuel furnaces, though much difficulty is now encountered in burning the bagasse, which is the waste product of the standard sugar plantation operations, under boilers. Furthermore, the value of the dried bagasse will be materially increased for sale to manufacturers of insulation board.

A most important advantage of my invention is the uniformity and fineness of the pulverized product, and the ease of grading said product into separate volumes of particles, each having a uniform degree of fineness, but that of one separated mass varying from that of others. This uniformity of fineness adapts each graded mass for most eflicient and economical treatment in the various chemical steps now employed in producing paper, rayon, viscose and similar cellulose products, while the coarser and more fibrous portions of the resulting product might be used in paper making as mechanical pulp. The preliminary mechanical treatment of fibrous vegetable products for use in the cellulose industries has heretofore usually produced particles of varying size intermixed one with another, with the results that only a. certain percentage thereof were properly modified by the reagents employed in the subsequent chemical treatments required, the coarser particles being under-treated and the too fine ones being overtreated; the practical result from this unsatisfactory condition of the mechanically treated material being a practical failure or prohibitive costs due to waste in the process. The uniformity of the product of the present invention is advantageous in remedying this difficulty.

Also, the method of my invention, if applied to wheat straw after soaking it in water, or in some helpful cheap liquid chemical, may be used to produce an evenly and finely pulverized product which can be most advantageously used in the chlorination or other chemical or mechanical treatment of wheat straw.

It is apparent that some pretreatment may be given to the material before applying pressure as described and in using the term natural cellulosic material in the claims, reference is made to the natural cellular structure of the material. and it is not intended to exclude such preliminary treatment as debarking, cutting into strips, etc., soaking in liquids, with or without previous drying, and other steps which do not substantially alter the natural cellular structure.

' One form of apparatus usable in carrrying out the method of my invention is illustrated somewhat diagrammatically in the accompanying three-sheets of drawings, in which Figure 1 is a side elevation of the roll press with partsbroken away and'others shown in section, portions of feeding and discharge attachments thereto-being also shown;

.Figure 2 is a similar plan iew; and

Figure 3 is an enlarged vertical cross section taken on line 3-3 of Figure 1, said feeding and discharge devices being shown more in detail,

the inner roll 4 cooperating therewith in themanner fully described in the above noted Patent No. 2,196,651. Said roll 4 is journaled in and be:- tween the swinging housings 3, 3, which are pivoted to the main frame at I. The upper ends of these housings are connected by pivots l to the lungers i4, i4, reciprocable in hydraulic cylinders l5, Iii, which are mounted in the upper portion of the main frame I. The pipes l6, it connect the cylinders with a source of-pressure, preferably of the type illustrated in Figure 4 of my Patent No. 2,229,143. An outer roll 24 is joumaled in the fixed housing 9 on frame i in such position that the ring 2 may be pressed against it in a horizontal direction by the inner roll 4.

Each of rolls 4 and 24 is mounted ona shaft 5 journaled in roller bearings i, the bearings for inner roll 4 being supported in the pivoted housings 3, 3, and those for outer roll 24 being supported in fixed housings 9, 9.

The great pressure exerted by the hydraulic apparatus above described when fluid is admitted to the cylinders through pipes l8, l8, under several thousand pounds pressure to the square inch, will suffice to hold the ring 2 compressed between rolls 4 and 24 in substantially the position shown in Figure 1. With this arrangement the ring may dip upon introduction of material into the horn angle beneath the roller 4, whereupon the apex of the horn angle is advanced in the direction of rotation of the ring and roller 4; The ring, however, may be supported by roller bearings l0, Ill, journaled beneath it in frame i. These rollers may be mounted in yielding bearings as illustrated in my prior Patent No. 2,229,143, so that the ring can dip against the controlled resistance of the rollers. The ring 2 may be lo'osely held against axial movement by side-plates H, H, each having a generally halfcrescent shape and being held in osition by supports bolted to them and to the main frame, as indicated at 26 in Figure 1.

The inner roll 4 is driven by any suitable power mechanismsuch as the electric motor 12 connected to its shaft 5 by the flanged coupling 20. Similarly outer roll 24 may be driven by another electric motor i3. If such independent electric drive be employed, the motors should preferably be of the synchronized constant-speed type and the diameter of roll :4 should be suillciently larger than that of roll 4 to permit it to roll on the outer circumference of the ring 2 without either roll having to slip at its point of contact with a surface of ring 2. Said motors are shown supported on brackets 82 and 33, respectively.

Alternating current of fixed cycle timing would be supplied to the motors from the service mains indicated at 21, 21, in Figure 2and the local reater degree ofdrag between its surface and the inner surface of ring 2 with which it would be in contact than would occur when both rolls 4 and v 24 are each positively driven.

The laterally separated upper sections of the main frame I may be tied together by a tie-bar flowing from the compression zone between rollsheets, slabs or strips, for example, the sheets n andbolts n, l8,asshown.

l9 (Figures 1 and 3) indicates a drainage out- ;let at the bottom of the space between the two main-frame sections through which any liquid 4 and ring 2 may be drawn oil.

When the hereinbefore described roller mill is used for disintegrating thin sheets, strips or slabs of wood, an automatic feeding apparatus for delivering such sheets consecutively to the interior of ring 2 may be employed, such as one comprising the magazine 2| in which a stack of such 22 like those used in veneering furniture, may be placed, preferably, each with its grain extending in the direction transverse to the axis of the mill.

These sheets, etc., rest on an endless belt 23,

which should be constantly driven so that its upper strand will feed each successive bottom sheet I out from under the stack, held back by the magazine 2|, into the chute 29, which discharges into the interior of ring 2, as best shown in Figure 3. Antifriction rollers 25 may be Joumaled in the lower portion of chute 29 to facilitate the transfer of the sheets 22 from magazine to mill, as indicated in said Figure 3. This feeding mechanism may be driven by a belt, as indicated at 30. Belt 23 may be provided with transversely extending battens 54, 54, (no thicker than sheets 22) which The particular apparatus herein illustrated for removing from the mill the crushed masses of wood fibre passing upward between the'gradually separating surfaces of roll 4 and ring 2, which both revolve in the direction of the arrows in Figure 1, comprises a scraper 3i hinged at on a supporting channel member 26 and having its free edge forced against the inner surface of the ring 2 by the tension spring 31, together with a similar scraper plate 32 hinged at 35a to av second channel member 38a extending parallel to the first mentioned one and having its free-edge held against the surface of roll 4 by a similar tension spring 31a. These channel members 36 and 33a may be supported in any convenient way, as by arms 43 fastened to the under-surface of a third requirements. For example, when the ring 2 is supported so that it will dip. it may be desirable to have the scraper ll extend more nearly parallel to scraper I2 so that it will slip along the ring more easily when the ring dips. V

39 is a horizontally traveling endless belt running over rollers ill, 40 supported between members 26, 38, and driven in any convenient way. as by power belt 62.

A bafie plate or guide It for the material discharged by belt 39 is also shown in Figure 3. The upper strandof said belt moves toward said plate, as indicated by the arrow in said Figure 3. This batlie plate is fastened to channel member 88 by bolts such as indicated at H.

The material dropping down inside said baffle plate so may be deposited in a combined hopper and 'chute 35 by which it may be delivered to a hammer mill such as indicated at 46, where it is pulverized mainly by the impact of hammers (not shown) caused to revolve by pulley er. Preferably the pulverized product is blown or sucked out from the hammer chamber by a fan (not shown) through a flne screen 58. The material passing said screen may be deflected downward by baiiie plate Q8, or otherwise delivered to any suitable receptacle 56 where it will accumulate in the form of wood flour, a quantity of which is indicated at 7 5|. The coarser particles are at all times retained in the hammer mill casing to be further broken up by the action thereof, so that the resulting finer particles progressively so produced may be ultimately blown or sucked through the screen.

Figures 5 to 9 inclusive of the drawings illustrate in diagram the manner in which pressure is applied to the substance being treated.

In operation, the work roll 6 rogates in a clockwise direction and takes the thrust of the hydraulic cylinder and'piston structure l5 and Hi and reacts upon the substance or material being treated. Power is applied to the shaft 5 of the work roll 6 at constant speed. The backup roll 24 rotates in a counter-clockwise direction, is supported as shown in the drawings in immovable journals 9. The hydraulic pressure applied by means of the hydraulic cylinder and piston structures l5 and M supplies a constant force through the floating ring 2 to the blanket of material being processed, such blanket being indicated by A in Figures 5, '7, 8, and 9 of the draw-.- ings. This force acting upon and in combination with the floating ring 2 and the work roll 4 produces a variable pressure on the material being treated. The floating ring 2 rotating in a clockwise direction has no journal bearings, but is constrained to rotate with its inner and outer faces parallel to the surface of the work roll} and backup roll 24.

The floating ring 2 is free to move with its center passing through an arc. The center of the radius of this are coincides with the center of;

thebackup roll 24. The arc of movement takes place only below the horizontal centerline a, b as indicated by the dimension F5 (see Figures 6 to 9).

The weight of floating ring 2 is supported by the hydraulic force on the assembly of the rolls and ring which tends to keep the centerline oi the rolls and the floating ring in line. This is the neutral position of the three rotating members and in this osition no work is being clone. The floating ring 2 is free to move vertically through its arc of movement, and movement is influenced entirely by the feed and resistance at the material being treated moving with the floating ring 2 through the compression are or pressure zone between the work roll 4 and the floating ring 2.

The hydraulic cylinder l5 applies a constant force applied to the roll and ring assembly.

Figures 6 to 9 inclusive of the drawings show the relation of the ring and roll assembly and the blanket of the material in process through four successive and distinct stages. These four stages or phases and synchronized relation of the main components continue to exist throughout the operation of the machine. The floating ring 2 is continuously sustained in balance by the hy-' draulic force and the reaction of the forces of resistance oi the substances or materials being treated against the work roll t.

Figure 6 shows the ring and roll assembly before any material to be treated is in the machine, or Just prior to feed acceptance 01 the ring 2 and rolls e and 24%. The floating ring 2 is slightly dipped below the center of the horizontal centerline 0, 11 due to the weight of the floating ring. The weight of the floating ring 2 also slightly moves the work roll 6 against the hydraulic pressure, and the apex of the horn angle or compression are between the floating ring 2 and the work roll 3 is slightly advanced causing an opening between the floating ring and the work roll on the centerlines c, b and c, d. This is an important characteristic of the machine employed in carrying out the present process in that the floating ring 2 and the work roll l are in contact, metal to metal, at the beginning of operation or at any subsequent cycle when the material being treated has ceased to move due to intermittent operation. This relation continues to exist until the material being treated is fed into the machine and the forces-of resistance of material change this balanced relation of the floating ring 2.

Figure 7 of the drawings shows the next step wherein the feed of the material being treated has taken place with the work roll surface and has passed through the initial pressure zone. The material reaches the point of feed acceptance in comparatively loose form so that it passes through the first stage of compression at a low pressure of resistance. However, since the floating ring 2 is in balance even this low pressure causes an additional dip of the floating ring 2 against the hydraulic forces applied, advancing the apex of the horn angle or compression are as shown. The resistance of the material being treated, indicated by n, is reacted upon by the force component R2 and resistance r; satisfying the balancing action of the floating ring 2. R2, ara=Ra, a: where Ra plus Ra equals R the force resulting from the hydraulic thrust.

Figure 8 illustrates the balancing forces on the floating ring 2 when the material has passed the line of force c, d. Due to the acute angle formed by the work roll 4 and the floating ring 2, the material is forced through the successive pressure zones in the compression are or pressure zone under compression, setting up a resistance which .reacts against the floating ring 2 and moves the asveocc plete blanket A of material passing through the compression are or pressure zone. and shows the action of the ring and roller type of hydraulic press upon the material. The floating ring 2 is allowed free movement' up to the point of the maximum volume of the material being treated, for the required production. It will be noted that the pressure force is applied to the material being treated through a line contact, or the tan-' gents of the backup roll 24 and the floating ring 2 on the centerline cd. After the material or substance being treated passes through this line of contact, the total pressure of force It divides into two force components R: and R3. The floating .ring 2 is free to move up or down to balance the on the full blanket A or the material takes place and the pressure is always distributed over the entire blanket. There is, therefore, no concentration of pressure forces at any one point to create shear through the blanket of the material in process; and consequently thepressure is applied to the material in process in a gradually increasing degree as the material moves upwardly through the compression are or pressure zone and with equal distribution over the blanket in any pressure area within the pressure zone.

The force resultant R which always coincides with the centerline c, d shifts continuously to balance the'equation R2$a=R3$a which determines the dip of the floating ring 2.

This type of ring and roller hydraulic press will Q separate the fluids or liquids from the cellular structures of various speciesof plant life through the medium of a cold (atmospheric temperature) process. This is accomplished by means of a progressive variable pressure being applied in the manner as above described and as particularly illustrated in Figure 5 of the drawings.

The base height of the compression space or pressure zone CB1. is influenced by the point of free acceptance and volume of maximum feed of the material being treated. The apex height of the compression arc CAh is determined by the ratio of the inherentvolumes of the material CB1; and CAh. Expansion and release of the processed material takes place beyond the apex CAh. The compression are between 0311 and CAn in the pressure zone or compression arc and the pressure on the material being treated produced by the hydraulic cylinder 15 varies in intensity throughout the entire compression are or pressure zone as indicated by the magnitude of ordinate of force I and resistance 1' shown. The resistance of the material to compression varies with the type of material being processed. The material, containing voids and moisture passes through the pressure zone or compression arc under a gradual increase in pressure, from zero to maximum pressure in pounds per square inch, or

per line inch of width of material being treated until the material reaches the apex .CAn. This characteristic of the continuous ring and roll type hydraulic press allows for free expression or extrusion of the liquid in the opposite direction to the movement of the material, 1. e., the fluid or liquid expressed always moves or flows from a zone of higher pressure in the compression are to a zone or lower pressure. never to azone or pressure higher than the one in which it is extracted, and. consequently the liquid carriesaway heat which is generated by the expressing action so as to prevent heating of the liquid, material being processed, and apparatus. As illustrated in Figure 5 of the drawings, the pressure zones which are indicated by the numeral 60 to I! inclusive increase in volume gradually in the direction of fluid or liquid extrusion, so that the water as a carrying agent of the liquid components moves from a zone of higher pressureand restricted area to that of a lower pressure zone and increasing area in successive steps.

In processing any particular type of material, the maximum pressure required is selected by experience or trial. and is of such a magnitude as to enable the release 01' all or such approximately predetermined quantity of the liquid content from the material being treated as desired so that the material issuing from the compression are or pressure space will be in a dry, porous, friable condition entirely free from any gums or any material which .would be detrimental in the subsequent pulverizing and screening steps of the present invention. Y

It will be seen from the foregoing description that since the rolls 4 and 24, and the floating ring 2 start out at the beginning of an expressing action in metal to metal contact, and that the opcrating surfaces 'are' parted by synchronizing terial, the compressible cellulose phase is always equally permeated during the compression action with liquid. Thus the flber or cellulose structure is being dehydrated in balanced volume to the moisture present, as related to the applied pressure as it progresses through the pressure area or horn angle, and there is no sealing of the cellulosic structure taking place during the bursting and disruption of the fluid-containing cells, and no impervious restriction is placed on downward fluid extrusion through the incoming material. Maximum extrusion for a given pressure having been secured at the flexibily advancedapex of the assembly, the remaining residual and/or bound moisture exerts an outward cellular bursting pressure, leaving the material in a fibrillated, noncompressed condition readily pulverized by variousapproved types of pulverizers.

In instances where the present Processes are subjected to subsequent chemical treatment such as now employed in making paper, rayon, Cellophane, and similar cellulose products, a stabilized base is provided with the percentage of the deleterious content being definitely known, thereby step or steps.

In Figure 4 I have shown a flow sheet, or rather a complete diagram forthe layout of a of logs, or other supply magazine. from which they may be conveyed one by one to any proper apparatus for stripping oil the bark (such as that known as a drum-barking machine") indicated at 62. Such stripping, of course, might be done by hand. The stripp d bark may be conveyed to a machine for subjecting it to the enormous pressures required in my process. preferably one of the type illustrated in Figures 1, 2 and 3 herein, said apparatus being here indicated at i This disintegrator may include a pulverizer and screen similar to that illustrated at 45, 48 in Figure 3, and the disintegrated bark might then be used in the arts as desired, its finely comminuted condition facilitating the tanning and other processes for which bark is now used. The stripped logs might be transferred to any suitable gang-saw apparatus indicated at 63 by which they may be cut longitudinally into thin slabs as is now done in the manufacture of veneer strips. These may then be stacked in magazine 2! (Figure 3) and put through the disintegrator l in the-manner pre viously described.

Preferably the logs would be cut during the spring and supper when the sap is up, and this sap and any other contained liquids may be expressed by the great pressures used in my process and allowed to fiow off through a conduit like is shown in Figure 3. If the logs were dry the cut stripsmay preferably be soaked in water before being fed to disintegrator I. It further disintegration is desired, the friable, dry product of the roller mill 8 may be fed from the roller mill to some convenient screening apparatus indicated at 64, such as a rotary screen with perhaps tumbling materials therein, and any fragments or too long fibres in the product of disintegrator I could there be screened out and, if necessary, processed again by passage through a second, smaller disintegrator indicated at l. The fine particles passing through screen 84 may be used or carried directly to a hammer mill 46 where they may be joined by the product of the second disintegrator l and be further pulverized, the finer portion being blown through a 50 mesh screen which might either be a part of the hammer mill 46 or a separate apparatus as indicated at 48. The coarser particles obtained by these pulverizing and screening steps may be deposited in collector H and used in certain kinds of coarse paper making or other commercial operation, in which what is now known as "mechanical pulp is usable. The finer particles passing through screen 48, or (if desired) the entire product of the hammer mill 46, may be then put through a second stage operation by passage through another hammer mill 46 and the product blown through a 100 mesh screen, either forming part of said hammer mill or being a separate apparatus (as indicated at 48), and the coarser particles isolated by this last screening operation then deposited in collector 12, being useful as a coarser type of wood flour in making plastics and similar apnoea products. Whilethe more finely commlnuted particles which have passed the mesh screen, or (if desired) the entire product of the previous step, can be passed through another pulverizer employing a 200 mesh screen, as indicated at 48", or through such a pulverizer and then through a screen indicated at 48 The particles passing through the 200 mesh screen might then be deposited in a third receptacle I3 and be usable for making high grade rayon, Cellophane, etc., while the coarser particles which cannot pass the screen may be delivered to receptacle I2, to mingle with those which have failed to pass the 100 mesh screen 38.

The products for use in paper making should consist in part, at least, of short fibres, while those to be used for making rayon, etc., need not have any fibrous formation whatever.

It is obvious that many variations may be made in the above suggested procedure, depending upon the material being treated or the products desired. For example, some or all of the various grades separated as described above may be used to advantage in the chemical treatment, such as the sulfate or sulfite process, for the preparation of wood pulp for use in the manufacture of paper or other cellulose products.

By preparing wood flour as described above, a portion of the liquids that are undesirable in subsequent treatments may be removed and the wood flour may be treated under conditions whereby the addition of chemicals or other subsequent treatment may be more accurately controlled.

Also, in the recovery of rubber from Castillo elastica, the bark of that plant may be treated as described herein to put it into a uniform finely divided condition particularly suited for recovery of its rubber content by means of solvents, etc.

While I prefer to use the type of hammer mill on the market in which materials are pulverized by the impact of swinging blades called hammers while said material is in air suspension and then the pulverized material so produced blown or sucked by a fan through a suitable screen, other forms of impact pulverizer could be used, such for instance as the old cyclone pulverizer type in which oppositely rotating propeller wheels enclosed in a casing throw the particles of materials back and forth up against one another and at the same time create sufiicient air draft to carry the more finely pulverized materials up through an outlet to a proper collecting bin or cyclone separator.

Various forms of apparatus other than those herein shown, described or suggested may be used in operating on natural or artificial cellulose structures in accordance with my invention,

so long as the same are crushed by mechanical pressure sufilcient to reduce them to friable masses, and then pulverized, preferably by impact in air suspension, to produce the finely comminuted final material herein described, or so long as any such modified procedure is within the definition of any of the appended claims.

Thus, while the direct coupled electric motors i2 and 13 are here illustrated as the roll driving mechanism for the sake of simplicity and flexibility, one or another of the gear mechanisms shown in Patent No. 2,196,651 or in Patent No. 2,229,143 could be employed in place thereof in ractice.

Also, the endless belt for feeding the wood sheets from the magazine to the roller mill might be replaced by some form of reciprocating pusher (suchasisindicated atilinl 'lgure 3) ofthetypecommonly used in handling cards which are bein punched in a tabulating machine, and in addressing machines employing card stencils such as that shown in Patent No. 538,403, granted F. D; Belknap, April 30, 1895. I

Claims directed broadly to the method described herein for preparing separated cellulose fibres from a cellulose-bearing body are being prosecuted in applicant's copending application Serial No. 195,776.

I claim: I

1. A process for comminuting natural cellulosic materials, comprising moving a cellulosic substance embodying cell-contained liquid through a pressure zone and gradually increasing the pressure on the blanket of substance from the point of entrance to the point of exit of the pressure' zone and applying the pressure to the blanket of material passing through the pressure zone in such manner that equalized distribution screen and continuing its direct passage to a mechanical pulverizer, pulverizing the screened or dehydrated friable mass in the mechanical pulverizer, and continuing the passage ofthe material through a' series of screens and mechanical pulverizers until a final product of the desired fineness'is provided.

2. A process for comminuting natural cellulosic materials containing its normal liquid content,

comprising. passing thematerial to be treated upwardly through a pressure zone, extracting liquid constituents fromthe substance byapply ingyielding pressure in progressively increasing degree as the substance moves upwardly'through the pressure zone, said'increasing pressure advancing sufiicientlyfrom the minimum to the maximum degree in said pressure zone and dispressure, zone in such manner as to burst liquid-containing cells between the fibers of the cellulosic material and release their liquid sively increasing degree as the substance moves upwardly through the pressure zone and advancing the pressure beyond the line of direction of maximum pressure application by shifting one A 1 to always fiow from an area of higher pressure to an area of lower pressure, passing the dehydrated iriable'mass directly to a mechanical pul verizer, and pulverizing the dehydrated friable mass in the mechanical pulverizer.

4. A process for comminuting natural cellulosic materials containing its normal, liquid content, comprising passing the material to be treated upwardly through an upwardly tapering pressure zone, extracting liquid constituents from the substance by applying yielding pressure in progressively increasingdegree as the substance moves upwardly through the pressure'zone and advancing the pressure beyond the line of direction of maximum pressure by shifting one side of the pressure zone upwardly relative to the opposite side in accordance with the resistance of the material to compression, said increasing pressure advancing sufiiciently from the minimum to the maximum degree in said pressure zone to burst liquid-containing cells between the fibers of the cellulosic material and release their liquid content while reducing the fibrous material to a porous friable mass,allowin'g the released liquids to always fiow from an area of higher pressure to an area of lower pressure, passing the dehydrated friable mass directly through a mediummesh screen, continuing its direct passage to a mechanical pulverizer, and pulverizing the screened dehydrated friable mass in the mechanical pulverizer.

5. A process for comminuting natural cellulosic materials containing its normal liquid content, comprising passing a material to be treated up tributed over the blanket of material in the content while reducing the fibrous material to a porous friable mass, allowing the released liquids to always ilow froman area of-higher pressure to an area of lower pressurein the pressure zone, passing the dehydrated friable mass directly through a medium mesh screen and continuin its direct passage to a mechanical pulverizer. pulverizing the screened dehydrated friable mass in the mechanical pulverizer, and continuing-the passage of the pulverized material alternately through a series of screens and mechanical pulverizers until a final product of the desired fin'eness is provided.

3. A process for comminuting natural cellulosic materials containing its normal liquid content. comprising passing the material to be treabd upwardly through an upwardly tapering pressure zone, extracting liquid constituents from the substance by applyin yielding pressure inprogreh wardly through an upwardly tapering pressure zone, extracting liquid constituents from the substance by applying yielding pressure in pr r s sivelyincreasing increments as the substance moves upwardly through the pressure zone and advancing the pressure beyond the normal line of direction of maximum pressure application by shifting one side'of the pressure zone upwardly relative to the opposite side in accordance with the resistance of the material to compres-' sion, said increasing pressure advancing suillcientl from the minimum to the maximum degree in said pressure zone to burst Iiq'uid-containingcells between the fibers of the cellulosicmaterial and release their liquid content by retiming the fibrous, material to a porous friable mass, allowing the released'liquids to always fiow from an area of higher pressure to an area of lower pressure, and passing the dehydrated fria- 1 ble mass through a series oi screens andmechanfineness is provided.

namzw a. s'racou.

- al pulverizers until a final product of the desired

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