WO1995015252A1

WO1995015252A1 - Processing lignocellulosic agricultural residue

Info

Publication number: WO1995015252A1
Application number: PCT/US1994/013931
Authority: WO
Inventors: George H. Sparks
Original assignee: Bio-Sunn Corporation
Priority date: 1993-12-02
Filing date: 1994-12-01
Publication date: 1995-06-08
Also published as: CA2177984A1

Abstract

A process for forming molded articles from partially delignified non-woody lignocellulosic materials (10) is disclosed that includes forming a mass of fibrous pulp partially delignified lignocellulosic material from a water suspension thereof, and separating (19) the mass into pieces of a size suitable to an airborne tumbling and drying operation. The pulp is subjected to the tumbling and drying operation (32) such that the fibers are sufficiently separated and aligned to be formed into an interconnected mat or web (46). The mat or web is subjected to sufficient pressure (48) to enable shapes to be molded from a continuous web and articles are molded from the web using a molded press. A water resistant coating (50) may be applied to the mat. A process of delignifying non-wood lignocellulosic material is also disclosed.

Description

PROCESSING LIGNOCELLULOSIC AGRICULTURAL RESIDUE

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention is primarily directed to the digestion or breakdown of agricultural lignocellulosic residue material in a manner that allows the lignin to be readily separated from the fibrous or cellulose constituent and particularly wherein the fibrous material or cellulose constituent is further processed into useful, self-adhering molded shapes. The process of the invention accomplishes the breakdown, i.e., delignification of rather complex non- woody agricultural materials which are not readily broken down naturally, such as flax straw, for example, without strong alkali materials, using only water and steam and expansion. The lignin is separated from the resulting cellulose fiber pulp of the exploded straw and the fibrous material processed into a substantially dry self-adhering moldable mat of material which can be formed into desired useful shapes in a subsequent pressing operation. II. Discussion of the Related Art

Certain agricultural residue materials such as flax straw, because of their chemical makeup, do not readily break down naturally if plowed under the soil after the useful crop is removed and so remain to be disposed of otherwise. Such materials do contain a certain useful fibrous (cellulose) content, lignin, hemicellulose and certain other polysaccharide nutrients if these constituents can be released and separated economically. The processing of these non-woody materials into useful products and environmentally neutral, readily assimilated residues would result in a profitable use for what is otherwise an expensive cumulative disposal problem.

Processes and apparatus which enable breakdown and delignification of lignocellulosic materials including woody materials and non-woody agricultural residues or other such bio-mass materials are known. One such process is described in related patents to Tyson (U.S. Patents 4 842 877 and 5 023 097, in which the non-woody lignocellulosic substrates are treated with an aqueous medium of strong alkali, such as sodium hydroxide, (at pH 10.5-12.5); optionally, the substrate is also treated with a chelating agent to chelate metal ions in the material, particularly if it is to be used as an animal feed stock. The material is fed to an extruder in which heat and pressure applied in an oxygen atmosphere and in the presence of an amount of hydrogen peroxide. The material explodes upon emergence from the extruder and the exploded product is suitable for ruminant feed stock, dietary fiber or as absorbent fibers.

Other processes for delignification include use of steam in combination with lower aliphatic alcohols and/or ketones as disclosed in Sinner et al (U.S. Patents 4 742 814 and 4 520 105). Foody (U.S. Patent 4 461 648 uses steam cooking followed by rapid depressurization (explosion) to process hardwood chips and agricultural residue materials and render the cellulose more accessible to micro-organisms, enzymes and the like, so that it can be used or digested by ruminants. Thompson, in U.S. Patent 4 307 121, uses water with Cl₂ as an oxidizing agent to solubilize edible portions of cellulose from agricultural by-products such as soybean hulls.

Attempts have also been made to mold articles using the delignified fibrous material, however, such prior processes have produced results that have been only partially successful. Such processes have not been able to produce usable molded products that are economically competitive with available alternatives.

The present invention contemplates a process for separating useful fibrous pulp constituents from lignocellulosic materials, particularly non-woody agricultural residue which lend themselves to such processing. The invention further contemplates processing the separated fibrous material into useful molded articles of commerce and includes the articles produced.

Accordingly, it is a primary object of the present invention to provide a simplified process for separating useful fibrous pulp material from lignocellulosic feed stock, particularly agricultural residue feed stock.

A further object of the present invention is to produce a fibrous material which is readily formed into a mat and processed into self-adhering molded articles. A still further object of the present invention includes a method of straightening and aligning fibrous cellulosic materials separated from lignocellulosic materials in a manner which enables them to be readily formed into a mat and molded into self-adhering shapes. SUMMARY OF THE INVENTION

By means of the present invention, the delignification separation of lignin from fibrous cellulosic constituents to release useful fibrous pump in such problem agricultural residue materials as flax straw is simplified. The fibrous pulp material is further processed to straighten or align the fibers, which can then be formed into mats and molded into self-adhering shaped articles without the need for additional adhesive or reinforcing agents. Coatings may be used to retard possible degradation from moisture or the like.

In accordance with one embodiment of the invention, flax straw or other lignocellulosic material of interest is shredded to the desired size, normally about 3 inches (-^• 8 cm) or less in length, and combined with an amount of water that is absorbed by the material. The wet or moisturized material is continuously fed into the receiving end of a pressure cooker in the form of a screw type extruder- expander, or the like, where the wet straw is compressed in the range of 75 psi to 200 psi (5 to 14 kg/cm²) and an amount of steam added to the compressed straw mixture as it moves toward the exit end of the extruder-expander. The extruder-expander operates at a very high internal pressure in the discharge area (s500 psi to 3000 psi or 35 kg/cm² to 210 kg/cm²) and as the material discharges through preferably a central orifice, the material literally explodes out of the barrel. The exploded material, generally in a fibrous pulp form, undergoes a hot water agitation step in which much of the lignin constituent is leeched and washed out of the pulp. While complete delignification is desired, it has been found that the process produces sufficient separation that a very useful fibrous pulp for making molded articles results and the removed constituents are suitable for broadcasting back on fields or as animal feed ingredients.

The washed material is then rolled or compressed to extract the bulk of the remaining lignin-laden water from the fibrous pulp which becomes a compressed wet cake. The compressed cake is subject to a rotating chopper device which breaks up the cake to what becomes a substantially chunk, pellet or granular form.

The chopped material contains tightly wound and uncooperative fibers. The granules are treated to a pneumatic agitation in which the granules are borne along by air conveyor devices and caused to tumble and strike obstacles and themselves repeatedly. This treatment extracts moisture from the material and causes the compressed granules or pellets to open and the fibers to assume a relaxed or straightened and aligned form. The pneumatic agitation includes subjecting the material to a drying operation which includes feeding it serially through one or more cyclone-type dryers sequentially while constantly moving the material using a pneumatic conveying system. Moistened air is constantly removed from the top and the fibrous pulp material from the bottom of each cyclone dryer. A substantially dry fluffy fibrous pulp is produced in which the fibers themselves are substantially straight or aligned and readily cooperate to be formed into a mat of material of any desired thickness. The mat is further compressed so that it may readily be conveyed to a press and molded in a compression molding system to form the desired part.

It should be noted that an amount of material, such as an oil or wax to prevent water damage to the molded part, can be coated on the compressed mat prior to molding to protect the surface of the final molded part. The material used for coating preferably should be one such that trimmings from the molded parts can be recycled to the shredder without adding undesirable residues of materials to the process.

One aspect of the invention also includes the recycling of the hot water used to extract the lignin from the pulp. Since no strong alkali or other chemicals need be removed or neutralized, all that needs to be done is to remove the solids and the water can be recycled. This is accomplished by continually feeding the hot water effluent and cake compression residue material into an high-speed centrifuge in which the lignin and other solids contained in the suspension are separated from the water and the water returned to extract additional materials from pulp. The lignin and other solid materials are periodically expelled by the centrifuge and can be harmlessly be spread over fields or, if desired, used as a constituent for livestock feed. The preferred parameters with regard to the operation of the extruder/expander include initial compaction in the range of about 75 to 200 psig (5-14 kg/cm²) up until the high-pressure discharge end of the device is reached, the steam is added at a point where the material will be contacted by steam for a period from about 15 to 90 seconds prior to exploding, depending on the material being processed and other considerations.

BRIEF DESCRIPTION OF THE DRAWINGS The single Figure is a schematic flow diagram illustrating a particular mode of operation of the process of the invention. DETAILED DESCRIPTION

As previously discussed, the materials processed using the method of the invention comprise cellulosic materials which include cellulose and hemicellulose molecules in the form of highly ordered crystalline structures together with an amount of lignin, a phenolic aromatic polymer built up from phenyl propane repeating units which has no systemic structure and is present in the cellulosic material penetrating, surrounding and coating the cellulose crystalline fibrous structures. This combination is often extremely difficult for the normal soil or digestive bacteria to break down. Thus, if the material can be broken down quickly and artificially into constituents of which a significant portion can be further processed into commercially successful products, what is, in some cases, becoming an expensive disposal problem, can turn the use of these wastes into a profitable endeavor. While the process described in accordance with the illustrated embodiment of the invention involves the processing of flax straw, which is particularly difficult to break down naturally in soil or the like, it will be appreciated that many lignocellulosic materials will lend themselves to similar processing and can be used to produce molded articles in accordance with the actual scope of the present invention. Figure 1 depicts a schematic flow diagram of one successful process in accordance with the present invention. One size plant using this process has been built to operate at a feed rate of about 2000 lb. (900 kg) per hour. Smaller and larger operations including some with multiple lines are contemplated, of course. The raw materials supplied to the process may include large parcels of agricultural residue in the form of non-woody bio- masses. Flax straw, for example, is usually obtained in the form of large round bales weighing upwards of 500 pounds (225 kg) . They enter the process at 10, where parcels are initially dumped into a feed hopper as at 12 which allows the tightly compressed bale of material to separate and typically drop from a bottom discharge in the feed hopper onto a flat belt conveyor at floor level which conveys the material at a controlled rate upward through a metal detecting system as at 14, which may include magnetic metal removal devices in addition to devices to detect and warn of the presence metal objects which may be contained in the feed and which might detrimentally affect either a product of the process or any of the devices utilized in the process. The feed stock is then fed or drops off of the conveyor into the feed hopper of a shredding device at 16 which is typically an heavy-duty, high-torque shredder having a cutter configuration to optimize the desired shredded size and throughput rate desired for the process. Such devices are well known and one shredder that has been successfully used is equipped with rotating blades that rotate at a speed of about 30 rpm. The slow speed contributes to long life and it has been found that, at that speed, the shredder will operate without the normal dust and noise expected from other types of size reduction machinery. In one successful embodiment, the shredder was mounted atop a specially fabricated frame that elevated the shredder so that a flat belt discharge conveyor for the shredded material could be operated below the shredder with the shredded material falling directly onto the flat belt discharge conveyor.

Typically, a straw feed is chopped so that the stalk lengths are approximately 3 in. or less (<8 cm) . The flax straw or other lignocellulosic feed material is normally in a partially dried state such that it will readily absorb an amount of available moisture. The shredded straw or other bio-mass material is subjected to water spray at 18 in which an amount of water within the limit that will readily be absorbed, held on the surface or otherwise combined with the shredded material is sprayed on the shredded feed as it is conveyed from the shredding step 16 to a pressure cooker, which is preferably an extruder, at 19. The shredded straw is fed into the feed hopper of the extruder directly from the end of the discharge conveyor leading from the shredder to the extruder or pressure cooker.

At this point in the process, the divided, shredded feed material, in the case of flax straw, is approximately 70-90% straw and approximately 10-30% water. This applied water provides lubrication to the straw so that the straw will flow along the flights of the extruder smoothly. This water eventually also turns to steam and aids the pulping process.

The extruder is preferably in the form of a continuous extrusion cooker of a type used for producing textured vegetable proteins, for gelatinizing and expanding cereals or cereal-based foods, dry-expanded pet foods and the like. Such extrusion cookers are well known and generally commercially available. As the material is conveyed along through the many flights of the one or more screws of the extrusion cooker, the pressure increases to the range of 75-200 psi (5-14 kg/cm²) . The pressurization raises the temperature and additional water and heat are added to the extruder cooker, as the bio-mass is conveyed along, in the form of steam at 20. This occurs when the stream of straw material is about half way through the extruder, and being heated by the friction of the extruder flights. Steam is applied through a port or ports at any desired pressure at or above that in the extruder, typically a pressure from 80 to 100 psi (5.5-7.0 kg/cm²) , depending on the extruder pressure when the steam is infused. The amount of steam can be varied to add enough moisture to raise the moisture content of the straw being processed to as much as 100% of the weight of the straw. The steam is infused through the flowing mass in a manner such that the steam and straw are in contact with each other for a period from about 15 to 90 seconds, depending upon the desired results and class of feed stock used. During this time, the straw becomes a moist hot pulp and the pressure is mechanically increased to a range of from about 500-3000 psi (35-210 kg/cirf) . About one-fourth of the way from the end of the extruder a port may be provided for optionally adding a bleaching material such as hydrogen peroxide (H₂0₂) to the straw material being processed. The addition of hydrogen peroxide is to lighten or remove any dark color from or bleach the straw being processed into pulp. The hydrogen peroxide is typically at a concentration of from 15% to 50% H₂0₂. The amount added can vary from 2% of the weight of the straw being processed to 20% of the weight of the straw being processed depending on the amount needed to achieve the desired color removal. In addition to the lightening of the color of the pulp from the processed straw, the chemical reactions involving the hydrogen peroxide creates both additional heat and pressure. This added heat and pressure may be of value in increasing the output of the extruder and enhancing the completeness of the pulping.

The reacted or digested material is then exploded through one or more die orifices at 22 into a vessel through which a stream of moving hot water flows continuously. The explosion is occasioned by a sudden release of the pressure to atmospheric from the extruder into a vented chamber at the discharge end of the extrusion cooker. The extrusion cooker may be provided with a fluid- operated valve device to separate or isolate the water containing vessel from the internal portion of the extruder cooker during start-up and until the feed material has established the desired positive pressure within the extruder cooker.

The reason for creating the pulp, of course, is to separate the fibers in the straw from the lignin holding the straw together. The more complete the pulping is done, the easier the downstream efforts to process the pulp are accomplished. During the explosion, pulp is ripped apart and the fibrous material is released from the tight hold of the lignin bonding the fibers and coating the bonded fibers as it does in the natural state and, after exploding, the digested or cooked material is then suitable for the lignin or other non-fibrous residue material in the feed stock to be separated from the fibrous material by agitation in a hot water bath as at 24. The stream of recirculating flowing water at 22 is at any desirable rate and a range in flowrate of 15 gallons per minute to 150 gal/min (55-550 1/min) was used in one successful system processing about 2000 (900 kg) of flax straw per hour. The water is typically pumped at a pressure from 10 psi to 100 psi (0.7 to 7.0 kg/cm²) . This water is at a temperature from 130°F to 200°F (54°C to 94°C) .

Agitation from the water flowing through the piping further separates the pulp being conveyed. The pulp is conveyed to a tank at 24 that is filled with water at a temperature from 100°F to as much as 200°F (37°C to 94°C) . This tank is agitated by the water circulating in the system through the pump that is providing the flow of water for conveying the pulp from the chamber to the holding tank.

The components of the pulp are agitated in the tank until the fiber and plant residue reach a concentration of 20% of the water weight to 45% of the water weight. The mixture of hot water and pulp components are pumped from the holding tank to a belt press or other type of machine that squeezes the pulp at 26 and separates the fiber and outer plant residue from the lignin that has been dissolved in the water. The dissolved lignin and water mixture is pumped into a centrifuge 27 that separates the water from the lignin. The lignin is collected in a tank as a thick liquid or a mud or clay type of product that can be disposed of or further processed for other uses at 29. The water which can still contain some dissolved lignin, is returned to the holding tank to be used again. It is not necessary to dispose of this water. The pH of the water is from about 4 to 9 depending on feed and whether H₂0₂ is used.

While the water bearing lignin and other dissolved impurities are pumped into the centrifuge for separation, - l i ¬

the fiber that has been squeezed to remove the moisture is expelled from the exit end of the belt press or machinery to do this operation as a cake or mat of fiber. At the exit, the cake or mat is broken into small pieces or fragments at 28 by being subjected to a chopping step as by a heavy rotary chopper which is attached to the end of the extraction press. The chopper breaks up the cake of fibrous material into a material which is in substantially pellet or granule form to allow them to be dropped into an orifice of a pneumatic conveying device.

This material is then swept as by a vacuum into a pneumatic conveyor system at 30 which may be operated by means of one or more Venturi-type pump systems which create a suction in an entry duct into which the material is fed and carries it thereafter through a Y or T connection to an adjoining duct using a high-speed air stream. The separate granules or pellets of closed or tightly wrapped fibers are subject to a length of pneumatic conveyor 30 which may include a spiraled internal surface or other roughened surface such that many collisions occur between the conduit and the material being conveyed and between the pellets or granules themselves.

One successful Venturi-type pneumatic conveying device uses a blower hooked to an eductor which feeds into a length of flexible conduit or hose having either a rough or smooth interior surface. The exit end of the conduit is hooked to a drying device which is preferably a cyclone- type separator that allows the conveying air to be exhausted to the atmosphere at 34 and the fiber to be discharged downward into another conveying device 36 which, in turn, feed other serially connected cyclone separators as at 38 and 44. The exhausted air carries moisture from the fiber being conveyed into the atmosphere, also at 40, etc., and may be vented as desired. In this manner, during this conveying and cyclone drying operation, the pulp is both dried and broken from a small cake, pellet, granule or mat form into individual fibers. The individual fibers are beaten from their rolled up state to fibers that are dry, substantially straightened and separated from the mass of the cake to fibers capable of being formed into a substantially flat interwoven web or mat. The conveying and processing can be continued for as many cycles, i.e., through as many cyclone devices or the like, as are necessary to attain the required state of dryness and straightness.

It is sometimes necessary or desirable to add heat to the conveying air stream to be able to properly dry the fibers. This can be done in any well-known manner. Relative humidity of ambient air is one factor that determines whether the addition of heat is necessary.

The last pneumatic conveyor leads into the final cyclone of the series 44 which is positioned to discharge the fibrous material into a mat-forming chamber which feeds the material onto a moving flat metal conveyor belt which is known as a mat former inasmuch as the fibrous material forms a relatively uniform mat or web as it is discharged onto the conveyor at 46. It is this mat of fibrous material that is processed into usable shapes from the pulped and processed fibers. The conveyor for the mat forming operation may be addressed by one or more parallel connected cyclones that discharge or drop portions of fiber delivered to them by the conveying air. The actual mat formation on the conveyor is controlled from the mat forming chamber which is equipped with internal moving deflectors that distribute the fibers evenly during their fall to a flat metal belt. The moving mat forming belt positioned below the chamber and cyclone accepts the fibers as a pile or mat that is continuously being formed and removed from below the chamber. The speed of the belt determines the thickness of the pile of fibers or mat.

The moving mat consisting of an essentially evenly precipitated mass of dried fibers is next compressed to a processible continuous web using a mat forming press that may be attached to the mat former frame. The mat is transported through the mat forming press at 48 which is tooled with proper tooling for the thickness of the part to be formed. The mat forming press entraps the mat and compresses it to the desired thickness needed for further processing. Heat can be added during pressing if desired. The mat forming process is completed once the mat former press has closed about the mat on the conveyor from above and below, giving the mat body to allow further handling. In addition to the compression of the moldable portion of the mat, the trim or flash portion of the mat is simultaneously compressed an additional amount in narrow areas running lengthwise parallel to the direction that the mat is moving. These densely compressed strips or tracks are used to support and guide the mat into the press between the open molds. Guide members are provided that run the length of the press from the mat former to the final exit of the press. Those guides are stationary with respect to the frame of the forming press and firmly support the formed mat as it is cycled through the press. The final part or article forming press is tooled with mold halves that open and close about the horizontally supported mat to form a molded article. The mat is moved forward by the slide movement of the mat former toward the open molds in he forming press. The slide movement is accomplished by moving the mat former press forward a distance enough to satisfy the mold spacing of the molds in the article forming press. The mat former press presses the mat and, at the same time, is driven or moves forward toward the forming press. When the forward distance is satisfied, the mat former press opens, releases the mat and retracts backward away from the forming press along the mat being precipitated on the mat former conveyor.

Once the mat enters the forming press, the tooling closes on the mat extended between the open molds on guides. This closing applies pressure to the mat and a shape is formed. Heat and pressure form the molded article for as long as the mold is closed. When the preset time to form the article is complete, the molds are opened and the article is left suspended along with trim on the guides. The sequence is then set for the mat former press to close and again compress the mat and drive the newly compressed mat and the formed article suspended in trim along the guides in the forming press. The newly compressed shape is pushed forward by the incoming mat being pushed along tracks by the moving mat former press. The second set of tooling in the article forming press can be identical to the first set or be progressively different to further shape the article to its intended shape. This shape can be accomplished in as many steps as are necessary. The last station in the press is a die-cutting station at 54 where the finished article is die cut from the web of connected parts and trim or waste material. The molded die cut part is moved downward out of the press and the trim conveyed upward to a shredder that returns the train or flash to the pumping extruder for repulping. In this manner, a continuous web is fashioned into molded articles. Between the mat former and the press a wax or other waterproofing is optionally applied to the surface of the mat at 50 to make the final shape resistant to moisture and oil. This wax is preferably biodegradable and repulpable and so does not interfere with the reprocessing of the flash. Such materials are commercially available and competitive in price for this use. In this manner, the waste or trim from the molding operation can be safely recycled without concern for introducing contaminants.

The process of the invention has been used to make such items as flower pots to replace peat pots, trays and other types of containers primarily for uses in which biodegradability after short-term use is desired. It has been found that the compressed fibrous material self- adheres during the molding to an extent such that no additional adhesive material, plasticizer or other constituent is needed. The molded articles will eventually biodegrade and the sensitivity to soil, water, etc. , can be adjusted as desired with coatings.

This invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.

Claims

CLAIMSI claim:

1. A process for treating non-woody, partially delignified lignocellulosic fibrous material into a moldable self-adhering mat comprising the steps of:

(a) forming a mass of fibrous pulp comprising partially delignified lignocellulosic material;

(b) subjecting the fibrous pulp to a tumbling/drying operation to separate the fibers and render them suitable for forming an interconnected mat;

(c) forming a mat using randomly oriented fibers from step (b) ; and

(d) pressing the formed mat to form a cohesive structure.

2. The process of claim 1 wherein the fibrous pulp is squeezed from a water suspension containing fibrous pulp to form a cake thereof.

3. The process of claim 2 further comprising the step of breaking up the cake of fibrous pulp into a form suitable for airborne conveying.

4. The process of claim 2 wherein the water suspension further contains suspended lignin and including the further step of removing the majority of the suspended lignin by centrifuging the effluent resulting when the pulp is squeezed.

5. The process of claim 1 wherein the tumbling/drying operation further comprises subjecting the fibrous pulp to a length of an air conveyance and one or more airborne solid/gas separator drying devices.

6. The process of claim 3 wherein the tumbling/drying operation further comprises subjecting the fibrous pulp to a length of an air conveyance and one or more airborne solid/gas separator drying devices.

7. The process of claim 1 wherein the tumbling/drying operation separates the fibers.

8. The process of claim 5 including the step of adding heat during step (b) .

9. The process of claim 1 further comprising the step of compression molding the mat to form desired self- adhering shapes.

10. The process of claim 1 further comprising the step of applying a water-resistant coating material to the mat after pressing.

11. The process of claim 10 wherein the water- resistant coating material is recyclable with trim waste.

12. The process of claim 10 wherein the water- resistant coating material comprises a wax.

13. The process of claim 1 wherein the lignocellulosic material comprises flax straw.

14. The process of claim 11 further comprising the step of re-using the water of the water suspension after lignin removal by centrifuging.

15. The process of claim 9 further comprising the step of applying a water-resistant coating to the mat prior to compression molding.

16. A process for forming a molded article from partially delignified non-woody lignocellulosic materials comprising the steps of:

(a) forming a mass of fibrous pulp comprising a concentrated amount of partially delignified lignocellulosic material from a water suspension thereof;

(b) separating the mass of fibrous pulp into pieces of a size suitable for airborne tumbling/drying;

(c) subjecting the pieces of fibrous pulp to a tumbling/drying operation including the equivalence of a length of airborne conveyance and one or more solid/gas-type separator/drying devices, such that the fibers are sufficiently separated and aligned as to be suitable for being formed into an interconnected web; (d) precipitating the fibers to form a web of a desired thickness; (e) subjecting the mat to sufficient forming pressure to enable shapes to be molded from a continuous web of the mat; and

(f) molding articles from the web using a molding press.

17. The process of claim 16 including the step of applying a water resistant coating to the web of step (e) .

18. The process of claim 15 wherein the water- resistant coating material comprises a wax.

19. The process of claim 16 wherein the lignocellulosic material comprises flax straw.

20. A process of delignifying non-woody lignocellulosic material comprising the steps of:

(a) subjecting a moist biomass of non-woody lignocellulosic material of desired size pieces to heat and pressure in a continuously fed extruder cooker;

(b) contacting the biomass with an amount of steam in the extruder cooker such that the steam contacts the feed for a known time span during which the pressure rises rapidly to the range of 500 to 3000 psi (35-210 kg/cm²) ;

(c) releasing the pressure suddenly as the biomass leaves the extruder to explode the biomass to include a fibrous pulp;

(d) agitating the exploded biomass including the fibrous pulp in relatively hot water to separate the majority of the lignin and fibrous pulp and form a water suspension thereof; and (e) separating the fibrous pulp from the water agitation of step (d) into a mass of wet fibrous pulp.

21. The process of claim 20 wherein step (b) further comprises infusing the biomass with steam at a pressure at or above the pressure in the extruder cooker at the point of infusion and wherein the steam contacts the feed for from about 15 to about 90 seconds prior to explosion.

22. The process of claim 20 wherein the water suspension further contains suspended lignin and including the further step of removing the majority of the suspended lignin by centrifuging the effluent resulting when the pulp is squeezed.

23. The process of claim 22 wherein the waste water is recirculated to separate more lignin and fibrous pulp.

24. The process of claim 20 further comprising the step of adding an amount of H₂0₂ to the biomass in the extruder prior to the addition of the steam.

25. An article made by the process of claim 9.

26. An article made by the process of claim 16.

27. The article of claim 25 further comprising an amount of water-resistant coating.

28. The article of claim 26 further comprising an amount of water-resistant coating.