US3224925A - Fibrous products from barking waste - Google Patents

Description

Dec. 21, 1965 T. G. BRANDTS ETAL FIBROUS PRODUCTS FROM BARKING WASTE Filed May 21, 1962 2. Sheets-Sheet 1 BARKING WASTE COARSE F'BROUS SCREENING FRACTION AND SEPARATING CORK-LIKE FRACTION SELECTIVE BARK ATTRITION FRACTION REFINER WET MAT PRESS AND DRY INVENTORS THEODORUS e. BRANDFS DONALD E. HELLEUR BOARD ROBERT M. HOPKINS FIG. I PRODUCT RODRIGUE e. BOIVIN ,flma/u 2/ ATTORNEYS Dec. 21, 1965 -r. G. BRANDTS ETAL 3,224,925

FIBROUS PRODUCTS FROM BARKING WASTE Filed May 21, 1962 2'. Sheets-Sheet 2 BARKING WASTE DISINTEGRATION wooD SCREENING PARTICLES AND SEPARATING REFINER FlNES j: SEPARATION WOOD PULP BARK PULP BOARD FORMING WET MAT PRESS AND DRY BOARD PRODUCT FIGZ INVENTORS THEODORUS G. BRANDTS DONALD E. HELLEUR ROBERT M. HOPKINS RODRIGUE e. BOIVlN ATTORNEYS United States Patent FIBROUS PRODUCTS FROM BARKING WASTE Theodorus Gerardus Brandts, Donald Edmund Helleur,

Robert Montgomery Hopkins, and Rodrigue Gerald Boivin, GrandMere, Quebec, Canada, assignors to Consolidated Paper (Bahamas) Limited, Nassau,

Bahamas Filed May 21, 1962, Ser. No. 196,510 7 Claims. (Cl. 162-93) The present invention relates to novel sheet products formed from barking wastes and the process for producing them.

It is the practice among most manufacturers of wood pulp to try to remove as much bark as possible from their pulpwood. This barking of the wood results in large quantities of waste material which, generally, have been of little commercial value. However, to dispose of this barking waste while at the same time avoiding polution of various kinds, many pulp mills and especially those using wet barking methods, have had to burn this waste at some expense. Mills using dry barking methods can, of course, burn their waste somewhat more economically.

The components of barking waste for the purpose of this present invention can be classified and identified as fibrous and non-fibrous. The fibrous components consist of: pieces or particles of wood, which are dislodged from the woody section of the log during the barking operation; the gross fibrous fraction of the bark, often referred to as the inner bark or phloem; and finally that part of the outer bark or phellem which while somewhat corky in nature, still possesses a fibrous structure. The non-fibrous components consist mainly of the scaly outermost parts of the outer bark or bark cork.

The proportions and nature of the above components in the original barking waste and in the final products above will vary with such factors as:

(a) Method of barking, e.g. in the tumbling-friction method using rotating cylindrical drums (wet or dry) the proportion of wood can be quite high; whereas in high pressure water-jet methods the proportion of Wood may be low.

(b) The species of wood, e.g., in balsam fir, spruce, poplar (and to a lesser extent in some of the pines) the inner bark is long and stringy, distinctly fibrous in nature and fairly adundant, whereas in Douglas fir the fibrous fraction consists of relatively short, needle-like fibres.

(c) The method by which the pulpwood is transported to the mills, e.g. river-driven wood can lose much of its whole or outer bark in transit, whereas truck or rail transported wood has most of its bark intact.

(d) The time of year during which the barking or wood cleaning is being done.

Methods to separate these components have been the subject of much study, and examples of two successful separation methods are to be found in co-pending Vroom and Boadway application No. 673,131, filed July 22, 1957, now Patent No. 3,086,717, and in Brandts et al. application No. 84,282, filed January 23, 1961.

Fibrous sheet products, such as insulation board, are usually made from wood fibres, either groundwood and/ or steamed wood. Bark, heretofore, has usually been avoided because it was found to reduce the strength of the product and impart other undesirable properties. However, we have now discovered that this has been due "ice mainly to a lack of proper separation of the components and to the manner in which the bark was used.

According to the process of the present invention, barking waste is separated into a fibrous wood fraction, a fibrous bark fraction and a non-fibrous bark fraction. The fibrous fractions are then blended together in the desired proportions and formed into a pressed, dried sheet or board. Depending on the fines content of the fibrous fractions it may be necessary to remove some fines to produce a satisfactory product.

According to a preferred embodiment, the process of our invention involves separating the total fibrous fraction of the barking waste from the non-fibrous fraction as well as separating the wood-fibre (or woodpulp) component of the total fibrous fraction from the bark-fibre (or bark pulp) component, using methods similar to those described in the above mentioned co-pending applications;

subjecting the separated wood and, if necessary, also the bark pulps to a refining action in conventional refining equipment; removing a substantial portion of the fine material including polysaccharide-type material; blending these two pulps in the desired proportions; adding additional wood-fibre (or pulp) prepared in a conventional manner, which amount will depend on the composition desired for the final product and on the amount of woodfibre available from the barking waste; running the blended bark and wood pulps over a conventional insulating board Fourdrinier or drum-vacuum filter machine to form a wet mat; pressing the wet mat in a conventional press section; cutting the board into the desired sizes and drying the cut board in a conventional kiln.

In accordance with the method of our invention it is now possible to incorporate large amounts of barking wastes in commercial wood pulp products such as insulation boards without decreasing the freeness of the pulp, and to obtain without the addition of a separate binder a product which compares very favourably in physical properties, such as density and modulus of rupture with a commercial sheathing containing an asphalt binder.

The Brandts et al. method for treatment of barking waste mentioned above, involves a semi-dry separation technique. Here the barking waste is preferably reduced to a moisture content of below then, by a series of disintegrations and semi-dry screening steps, followed finally by a wet screening step, the fibrous portion of the barking waste is divided into a bark fibre fraction (or bark pulp) and a wood fibre fraction (or wood pulp).

The Vroom et al. method for component separation involves a wet centrifugal technique. An application of this technique in the present case involves: two Wet disintegrations, a wet screening step to separate the wood from the bark, then a hydraulic centrifuging to separate the fibrous bark component from the non-fibrous or cork component. The centrifugal separator is of the vortex, pressure-drop type such as described in the Freeman and Boadway US. Patent No. 2,927,693.

It will of course, be realized that any other method of separating the fibrous component from the non-fibrous component would be equally applicable.

FIGS. 1 and 2 are flow diagrams of 2 embodiments of the present invention.

The product and process of our invention will be better understood from a study of the following examples. It is to be appreciated that these examples are intended to be illustrative only and are not limitative on the scope of our invention.

Example 1.The barking waste discussed below is that from the early part of the barking season. The fraction separation is by the semi-dry method.

Spruce and balsam logs (approximately 50:50) were drum-barked. The drum barker waste was broken up and dewatered in a Stacomizer press (trademark of Stacom Industries, Inc.) to an average moisture content of 68% by weight and, referring to FIG. 1, the resulting bark was fed into a 36 single-runner disk attrition mill equipped with spike-tooth plates. The bark was then conveyed into a pilot plant size trommel which had a diameter of 18" a length of 6' and consisted of a screen having 4" square openings. The inclination of the trommel was 2" per foot; the speed 60 rpm. The screen was kept clean by means of air jets. (In commercial practice, larger size trommels would be used.) The material rejected by the trommel represented 62% by weight of the total barking waste fed to the trommel (on an oven-dry basis) and had a moisture content of 70%. This fraction contained 82% fibrous inner bark, 11% wood particles and 7% outer bark which also appeared to be mainly fibrous in structure.

The material accepted by the trommel represented 38% by weight on an oven dry basis and had a moisture content of 63%. This fraction was further separated over an 8-mesh vibrating screen into an accepted fines fraction (product 1) representing 15% by weight of the total amount of barking waste, and a rejected fraction representing 23% by weight of the total amount of Waste. The fines consisted of scaly outermost bark, bark and wood fibre debris, and dust.

The fraction that was rejected by the vibrating screen (e.g. Hum-mer or Tyler screen) was separated by means of a Sutton, Steele and Steele dry air float table (also referred to as a Kipp-Kelly specific gravity separator) into a cork-like chip fraction (product 2), representing 8% by weight of the total bark and a fibrous fraction representing 15% by weight of the total amount of bark. The fibrous fraction of the air float table or separator was combined with the fibrous or reject fraction from the trommel to give a total yield of fibrous material of 77% by weight of the total amount of bark.

The combined fibrous fraction was pulped in a singlerunner (SW 362) refiner manufactured by Sprout- Waldron Inc.; the plate patterns used on the rotating and stationary disks, respectively were: 16,808 and 16,8081. Energy consumption in this stage was 7.6 HP. da./ADT (horsepower days per air dry ton of pulp); the refining consistency was 6% and the plate clearance 0.075 inch. Under these conditions, the wood-portion of the fibrous fraction was reduced in size to a very slight extent, while the fibrous bark material Was reduced to fibre or near fibre dimensions.

The refined material was diluted to approximately 1% and screened in a small rotary screen, manufactured by Bitfar-Jung, equipped with 0.104 inch perforated screenplate. In the rotary screening stage approximately 7% of the original total barking waste was rejected as coarse wood particles (product 3); the remaining 70% (of the total barking waste) was accepted by the screen and con sisted mainly of bark fibre pulp (product 4).

The above bark pulp, product 4, was then used along with the woody material (product 3), to make insulation board. To do this, the following further steps were undertaken: the woody material, product 3, was fiberized in a disk refiner into a high-freeness wood pulp (when insufficient wood pulp was available, other waste wood, e.g. wood shavings, was fiberized along with product 3); the bark pulp (product 4) was put through a 610 Vorject (trademark of Nichols Engineering and Research Corporation) centrifugal separator or cleaner to remove the wood seeds and any residual bark cork; the accepted bark pulp from the cleaner was then passed over a screen to remove or wash out the very fine bark material or debris, and polysaccharide-type material, thereby converting it into a higher freeness bark pulp; the higher freeness bark pulp was blended with the high-freeness wood pulp in such proportions that the mixture had a TAPPI (suggested method T002 sm-5'1) drainage rate between 20 and secs. For this particular example the ratio of wood fibre to bark fibre was approximately 1:1.

The above mixed bark and wood pulp was used to form test insulating boards by a method and on equipment closely approximating procedures and equipment specified by the Structural Fibrous Materials Committee of TAPPI and described in suggested method T1001 sm-51. Not all of the equipment specified in this method was available and boards of 12 /2 x 18 /2" were formed rather than the 14.5 x 14.5" boards suggested by the TAPPI method. All boards were tested by the procedures given in the Canadian Government Specification Board Standards 11-GP2 and 11-GP-0 of January 22, 1960.

The results of these tests are shown in Table I under Example 1.

Under this scheme, bark products 1 and 2 are available for other uses (e.g. cork-type products, particle boards, etc.).

Example 2.The fraction separation is by the wet centrifugal method.

Referring to FIG. 2, a sample of whole bark or barking drum waste, from the late August barking operations, was fed into a 36" single-runner disk attrition mill. The attrition mill was equipped with spike-tooth plates for the purpose of shredding the bark. The shredded barking waste was then pulped in a single-runner (SW 362) refiner manufactured by Sprout-Waldron Inc.; plate patterns used on the rotating and stationary disks and control ring respectively were: 16,808, 16,808] and 17,709. Energy consumption in this stage was 11.4 H.P. da./ADT (horsepower days per air dry ton of pulp); the refining consistency was 10% and the plate clearance 0.080 inch. Under these conditions, little or no work was done on the wood present with the bark, but at the same time the bark fibrous material was reduced to fibre dimensions. In this example use was made of the SW-2 control ring; it is possible to use this ring to advantage when processing various types of barking waste.

The refined material was diluted to approximately 1% and screened in a small rotary screen, manufactured by Bilfar-Iung, equipped with a 3.2 mm. perforated screenplate. In the rotary screening stage approximately 8% of the original total barking waste was rejected as coarse wood particles; the remaining 92% accepted by the screen consisted of bark fibre pulp, cork and fines.

The coarse wood material was defiberized hot in a disk refiner into -a high-freeness wood pulp (when insufficient wood pulp was available other waste wood, such as wood shavings was fiberized along with the woody rejects); the bark pulp was put through a 610 Vorject (trademark of Nichols Engineering and Research Corporation) centrifugal separator or cleaner to remove the wood seeds and bark cork; the accepted bark pulp from the cleaner was then passed over a small centrifugal rotary screen equipped with 0.7 mm. perforated screen-plate to remove the very fine bark material or debris, thereby converting it into a higher freeness bark pulp; the higher freeness bark pulp was then blended with the high-freeness wood pulp in such proportion that the mixture had a TAPPI drainage rate of between 20 and 40 secs. The percentage of wood fibre in this blend was approximately Test boards were made from this bark-wood pulp mixture in a manner described in Example 1 of this text.

The results are shown in Table I under Example 2.

Example 3.-The method described in Example 1 was repeated for barking waste obtained late in the season when the percent of wood waste was very high in proportion to the bark. The proportion of wood pulp in the bark-wood pulp mixture was approximately 50%.

6 In making insulation board from bark pulp, however, several important aspects must be stressed. These are as follows.

One of the difficulties that had to be overcome in preresults are shown in Table I under Example 3. paring bark pulp was due to the heterogeneous nature of Example 4.The same procedure was followed as in the barking waste (discussed to some extent in the above). Examples 1-3 above except that wood pulp only made At some stages of the barking season the barking waste in the same way as for the above examples, is used (withmay contain only several percent of wood; while at other out the addition of bark pulp) to make insulation test times, especially at the end of the season, the amount of boards. The results from the testing of these boards is wood may run as high as 30%. The wood, however, is shown in Table I, under Example 4. relatively resistant to pulping while the tender bark fibre Example 5.-The same procedure was followed as in is not. Thus, care must be taken not to destroy completely Example 4, the wood pulp being a commercial pulp from the fibrous nature of the bark by too drastic a fiberizing an operating mill; the results are shown in Table I under action. Fortunately, as has been shown in the above ex- Example 5. amples, this wide difference in fiberizability can be made Example 6.The same procedure was followed as in use of, to bring about a separation of the bulk wood fibre Examples 1-3 except that in the present example, 100 from the bark fibre. The care that is required in the percent bark pulp is used to make test insulation boards. fiberizing or refining steps is also important in terms of The results from the testing of these boards is shown in maintaining as high drainage (freeness) level as is pos- Table I, under Example 6. The barking waste was sible. This will also tend to maximize the yield of bark from early season barking operations. fibre; too drastic a fiberizing will lead to the production of Example 7.-A commercial insulation board was prefines which will be lost in the fines removal step. Thus, pared in the conventional manner but without asphalt. a fairly fine compromise must be made between fiberizing Example 8.A commercial insulation board was prethe bark fibre sufiiciently that it will be accepted by the pared as in Example 7 except that l0l5% asphalt Was rotary screen, and fiberizing it too much. such that its included. drainage properties are adversely affected.

Example 9.In order to obtain information on how the The fines removal step is also an important part of barkwood pulp mixture might behave on a commercial our process. Since insulation boards are made at relamachine, several hundred pounds of pulp were prepared tively large thicknesses, the drainage rates of the pulp according to the method indicated in Example 2. The furnishes are a very important property of the pulps. That pulp was sized with 1.5% wax and alum at pH 4.4 and con is, generally the higher the drainage rate the better. The verted into an insulating board on a small pilot plant drainage properties of bark pulp were markedly affected Oliver vacuum filter (cylinder 3 feet in diameter, 2 feet by the amount of fines present in the stock. This fines wide). The wet board was pressed in a Downingtown u material arises out of fine material originally in the bark, press and dried in a Coe dryer at 300 F. and out of fines produced by the various disintegrating Throughout the trial the pulp performed in a satisfacactions taking place throughout the handling of the barktory manner. This short trial did not permit the developing waste. In addition to its effect on drainage, the presment of the best operating adjustments since the results ence of an excessive amount of fines adversely affects on dried board from a first trial would be needed for board shrinkage, density and drying rates; all these properguidance on subsequent runs. For example, thickness reties tend to increase with increasing fines content; the sults could not be exactly predicted in advance of the shrinkage may become so severe that the boards will warp trial, resulting in too high a caliper. By using a higher severely on drying. On the other hand, the presence of the pressure in the Downingtown press section a better caliper fines tends to increase the flexural strength :and rigidity of and density would have been obtained. The results are the finished board. shown in Table I under Example 9. This we believe to be due to the fact that while there is It is to be expected that the results would be even more a polysaccharide-type material associated with every bark favourable if the bark-wood pulp furnish had been run fibre which tends to enhance the bonding power between on a full scale machine. The larger diameter cylinder, in the fibres, the various process steps tend to concentrate particular, would contribute to higher strengths. this polysaccharide material in the fines portion, so that Table I Example Example Example Example Example Example Example Example Example 1 2 3 4 5 0 7 s 9 Description Test Boards Commercial Sheathing Bark- Bark wood Pulp Pulp Bark-wood pulp Wood Pulps No Asphalt Asphalt Percent bark pu1p 50 50 O 0 TAPPI drainage (sees 40 32 35 25 20 Freeness (0.8.) 685 720 681 735 763 Moisture after pressing (percent) 54.1 52. 7 67. 7 47. 8 50. 2 Drying time (min. at 300 F.) 150 135 100 90 Caliper (inches) 0. 509 0. 503 0. 502 0. 510 0.539 Density (lb./ft. 21.8 19. 2 17. 9 17.8 18.6 Modulus of Rupture:

(P.s.i. 512 474 480 233 279 (Corr. 20lb./ft. 440 512 600 290 320 Water absorption (percent v0 7 1 MO R proportional to the square of the density.

As the results in Table I indicate, the bark-Wood insulain the fines removal step, a balance has to be sought betion boards compare very favourably with present comtween what is desired in terms of pulp drainage, board mercial boards which have been strengthened through the shrinkage, drying rates, etc., and that desired for final addition of l0-l5% asphalt. board strength. In both Examples 1 and. 2 above, the

fines removal step takes place towards the end of the pulping steps, just prior to preparing the mixed wood and bark pulp furnish. The actual amount of fines that one should in fact remove, will depend on such factors as the nature of the barking waste, the method of bark separation used, the percent of wood pulp used, the board properties required, etc.

As mentioned previously, the removal of bark cork is imperative to the production of satisfactory board. Be sides contributing to lower board strength, its presence causes a dusting problem in the finished product and in addition gives a poor appearance to the product. In Example I, the majority of the cork is removed in trommel and vibrating screens and on the air table, while in Example 2, most of the cork is removed in the wet centrifugal cleaning operation.

A good. quality board stock should be free, strong and have spring back. Spring-back refers to the property of the formed mat to spring back to the desired caliper after it has been pressed. Boards having good springback can be pressed to low moisture contents thus achieving economy in drying Without permanent reduction in caliper. Bark pulp in itself does not have good springback properties, but when mixed with about 2050 percent wood pulp the resulting pulp spring-back is satisfactory. This then points out the importance of incorporating a wood pulp with the bark pulp to produce a satisfactory board. In addition, the inclusion of high freeness wood pulp improves the drainage properties of the machine furnish as Well as reducing the necessity of having to remove an excessive amount of fines, decreasing excessively the bark fibre (or pulp) yield and creating a pollution problem. The actual percent of wood pulp that is used in the mixed furnish will depend on the type of product desired as well as on the various other factors involved in producing the raw materials (e.g. method of separation, type of bark, etc.). Thus while one could produce an insulation board with a high MOR from an all-bark furnish, the spring-back and freeness would be low. As the amount of wood increases, the MOR tends to decrease but at the same time the spring-back and freeness tend to increase. This would indicate that the amount of wood can be varied according to the end product sought. As mentioned in Examples 1 and 2, where insufficient wood or wood pulp is available from the barking waste itself, additional wood or wood pulp may be obtained from any of the conventional sources.

Additional strength as well as flameproofing properties can be given to the bark-fibre insulation board by a process which is described in a co-pending application Serial No. 818,462; filed June 5, 1959, by Brandts, now Patent No. 3,092,537. Other properties which are improved by this process are: fungicidal, bactericidal and insecticidal resistance.

Care should be taken in the storage of bark. Pressed bark, still containing a considerable amount of moisture, tends to decay more rapidly than unpressed bark so that if it is necessary to store bark for longer than six months it is preferable to store it in the unpressed state. The

.main effect is a loss in yield; the fibrous material tends to lose its fibrous structure and eventually becomes Watersoluble or at least non-screenable or -filterable.

Although the above discussion is directed mainly to the production of an insulation board, it is to be realized that the primary purpose of this invention is a profitable use for barking waste. Accordingly, it is to be understood that our invention applies not only to the production of insulation board but to any other use which takes advantage of the unexpected properties of the product of the invention. Thus, a bark pulp in accordance with this invention can to advantage be incorporated as a component furnish with other wood pulps such as ground wood, kraft and sulphite pulps to produce various papers, paper boards and molded pulp products. In particular,

we have found that bark pulp blends well with unbleached kraft pulps since its dark colour readily matches that of the kraft pulp and the polysaccharide component in the bark pulp appears to be especially compatible with kraft fibre and tends to improve fibre to fibre bonding.

What We claim as our invention is:

1. The process for making fibrous boards from waste raw cellulosic material, which comprises disintegrating barking waste obtained from wood having a stringy fibrous 1O inner bark into a fibrous wood fraction, a fibrous bark fraction and a non-fibrous bark fraction, the disintegration being such that the wood fraction of the barking waste is substantially not disintegrated while the fibrous bark fraction is disintegrated to substantially fibre-size and the non-fibrous bark fraction is disintegrated to relatively fine dimensions, separating the said wood fraction from the said fibrous and non-fibrous bark fractions, further separating the fibrous bark fraction from the nonfibrous bark fraction, disintegrating the said wood frac- 20 tion to substantially fibre-size, blending together in suitable proportions the said disintegrated fibrous bark fraction and the said disintegrated fibrous wood fraction and forming the blend into a pressed, dried product.

2. The process of making fibre board from barking g waste obtained from a wood having a stringy fibrous inner bark, which comprises subjecting barking waste to a disintegration such that the wood fraction of the barking waste is substantially not disintegrated while the fibrous bark fraction is disintegrated to substantially fibre-size and the non-fibrous bark fraction is disintegrated to relatively fine dimensions, separating the said wood fraction from the said fibrous and non-fibrous bark fractions and disintegrating said wood fraction to form a fibrous wood fraction, further separating the fibrous bark fraction from r the non-fibrous bark fraction, removing at least a portion of the fines from said fibrous bark fraction, blending together said fibrous wood fraction and said fibrous bark fraction into a mixture containing at least 20% woodfibre and forming said mixture into a pressed, dried sheet.

3. The product of the process of claim 2.

4. A process for making fibrous boards from waste raw cellulosic material which comprises disintegrating a barking waste of wood and bark, the inner layers of said bark being of a stringy, fibrous nature, and the outer layers of a corky, non-fibrous nature, the disintegration being such that the wood portion is substantially not disintegrated while the fibrous bark portion is disintegrated to substantially fibre size and the non-fibrous bark portion is disintegrated to relatively fine dimensions, separating said portions, disintegrating said wood portion to substantially fibre-size, blending together in suitable proportions the said fibrous bark portion and the disintegrated fibrous wood portion and forming the blend into a pressed, dried board.

5. The process as claimed in claim 4, wherein additional disintegrated wood fibre from a source other than bark waste is added to said blend.

6. The process as claimed in claim 5, wherein said conventional wood pulp is a kraft pulp.

, 7. A process for making fibrous boards from barking .waste which comprises disintegrating a barking waste of wood and bark, the inner layers of said bark being of a stringy, fibrous nature, and the outer layers of a corky, non-fibrous nature, the disintegration being such that the rd ,wood portion is substantially not disintegrated while the fibrous bark portion is disintegrated to substantially fibre size and the non-fibrous bark portion is disintegrated to relatively fine dimensions, separating said portions, blending said fibrous bark portion together with a conventional ybvood pulp and forming the blend into a pressed, dried.

oard.

References Cited by the Examiner UNITED STATES PATENTS 1,349,112 8/1920 Weiss l62-93 (flther references on following page) 9 10 UNITED STATES PATENTS OTHER REFERENCES 2 923 7 5 3/1960 Kurjan 1 93 Kress: Use of Bark for Paper Specialities, from Paper, v01. XIX, Nov 4, Oct. 4, 1916, page 15. 3 2947655 8/1960 Eberhardt 241 24 Casey: Pulp and Paper, vol. 1, page 200, pub. by In- 3086717 4/1963 Vroom 241-24 5 terscience Publishers, New York, N.Y., 19'52.

FOREIGN PATENTS DONALL H. SYLVESTER, Primary Examiner. 446,696 2/1948 Canada. MORRIS O. WOLK, Examiner.

Claims (1)

1. THE PROCESS FOR MAKING FIBROUS BOARDS FROM WASTE RAW CELLULOSIC MATERIAL, WHICH COMPRISES DISINTEGRATING BARKING WASTE OBTAINED FROM WOOD HAVING A STRINGY FIBROUS INNER BARK ITO A FIBROUS WOOD FRACTION, A FIBROUS BARK FRACTION AND A NON-FIBROUS BARK FRACTION, THE DISINTEGRATION BEING SUCH THAT THE WOOD FRACTION OF THE BARKING WASTE IS SUBSTANTIALLY NOT DISINTEGRATED WHILE THE FIBROUS BARK FRACTION IS DISINTEGRATED TO SUBSTANTIALLY FIBRE-SIZE AND THE NON-FIBROUS BARK FRACTION IS DISINTEGRATED TO RELATIVELY FINE DIMENSIONS, SEPARATING THE SAID WOOD FRACTION FROM THE SAID FIBROUS AND NON-FIBROUS BARK FRACTIONS, FURTHER SEPARATING THE FIBROUS BARK FRACTION FROM THE NONFIBROUS BARK FRACTION, DISINTEGRATING THE SAID WOOD FRACTION TO SUBSTANTIALLY FIBRE-SIZE, BLENDING TOGETHER IN SUITABLE PROPORTIONS THE SAID DISINTEGRATED FIBROUS BARK FRACTION AND THE SAID DISINTEGRATED FIBROUS WOOD FRACTION AND FORMING THE BLEND INTO A PRESSED, DRIED PRODUCT.

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