DE2364939A1 - Process for the production of panels from lignocellulosic fibers with a total circulation of the production water - Google Patents

Description

DR. MULLER-BORt Dl ⁰ L-PHYS. DR. MAN ! TZ DIPL.-CHEM. DR. DEUFEL

D1PL.-IN3. GRÄMKOW PATENTANWÄLTE OO Q f QOQ

D / S / Bn - J 1134

28th EET. 1873

ISOREL

3, avenue du General de Gaulle Puteaix, Hauts-de-Seine, France

Process for the production of sheets from lignocellulosic fibers with a total circulation of the production waters.

The invention relates to a method for producing panels made of lignocellulosic fibers by the wet process, during which the production water is completely circulated will.

The factories for the production of sheets of lignocellulosic Wet route fibers consume large amounts of water, usually emitting large amounts of wastewater, the is loaded with fibrils and organic or mineral products that are in solution or in suspension and can be traced back to the wood that was used as the raw material, as well as to the various products that may be added during manufacture. Therefore, factories contribute to the production of panels from lignocellulosic fibers contributes to a significant extent to water pollution. 409828/0340

Dr. Müller-Borö Dr. Manitz ■ Dr. Interpret! - Dipl.-Ing. Finsterwald - Dipl.-tng. Grämkow Braunschweig, Am Bürgerpark 8 8 Munich 22, Robert-Koch-Strasse 1 7 Stuttgart-Bad Cannstatt, Marktstrasse Telephone (0531) 73887 Telephone (0811) 293645, Telex 5-22050 mbpat Telephone (0711} 567261 Bank: Central Cash Office Bayer. Volksbanken, Munich, account no. 9822 Post check: Munich 95495

Numerous methods have therefore already become known to purify production water for reuse. These processes use either flocculation or flotation of the various products that are in the drained water the molding device as well as in the waters exiting the presses. The separated solids are then re-mixed with the slurry prior to molding, while the purified water is recycled.

However, these methods work unsatisfactorily because then, if the concentration of the materials in the solution is high or they are in a colloidal state, their precipitation is very high is difficult. In addition, these procedures do not allow Total circulation of the production water.

When circulating Fabrikätionswässern without addition of fresh water, an increasing temperature increase is also noted that water, which can reach 80 to 90 ⁰ C. In this way, unfavorable working conditions are created for the workers who work on the part of the molding machine on which these water appear, and very rapid material corrosion can also be observed. In addition, the enrichment of circulating water with materials in suspension or in solution, most of which are susceptible to fermentation, gives rise to the formation of biological sludge which clogs the circulation pipes and the presence of which in the plates makes them very flammable in the dryers and spots are also formed on the surfaces of the finished panels.

The circulation of used production water also leads to an accumulation of organic acids in the pulp, which can be attributed to a fraying of the wood, so that the pH decreases progressively. Finally, an enrichment of the circulated water and thus of the pulp has with it in The result of the materials in the solution that there is a tendency for the plates to stick to the metal sieves that are located between

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see the plate surfaces and the steel sheets which can be used for hot pressing these plates.

The invention has set itself the task of addressing these disadvantages and a method of making sheets from lignocellulosic fibers with a total agitation of the production water without the addition of fresh water.

This procedure is essentially characterized by that by defibering wood chips in a defibering device lignocellulosic fiber obtained from the water vapor at the outlet under a via steam pressure of 6 to 12 bar the fiberizing device in a separator, in which a separation of the solid phases from the gaseous phase is carried out, is separated to the temperature of the to keep used water below 60 C at the exit This separator of the fiber contains a certain amount of circulating water that occurs during the entire production process Amount is added so that a slurry with 3% dry fibers is obtained, then an antiseptic is added to the slurry the pulp is refined in the usual way, then, if necessary, a neutralizing agent is added is used to maintain the pH at about 4 to 4.5, while also adding the amount of aluminum ions that is necessary for gluing the board, the pulp treated in this way is then diluted again with circulating water is then to adjust its concentration of solid, dried matter to 1 to 2%, this pulp is passed into the distribution box of the molding machine, the fiber pad, after being passed through this molding machine, cut to the desired length and in a Hot press is pressed under the usual conditions for obtaining a hard board, and all of these are different Measures accumulating water are collected and recycled.

The following preferred embodiments are provided:

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The separator in which the solid phases are separated from the gas phase, which is located at the outlet of the defibering device a cyclone separator is provided.

The antiseptic product added to the porridge consists of chlorinated ones Phenols such as sodium pentachlorophenate, formaldehyde or mercury derivatives.

The amount of antiseptic added to the slurry is between 0.015 and 0.1% based on the dry fibers.

The neutralizing agent for maintaining the pH value of the pulp near 4 to 4.5 consists of lime and / or sodium aluminate.

The aluminum ions, which are necessary for gluing the board, are supplied in the form of sodium aluminate in such an amount that _{corresponds to 150 to 300 mg Al 3} O ₃ per 100 g of the dry fibers.

The slurry that is fed to the distribution box can one also adds small amounts of a polyelectrolyte to prevent the fiber pad from dripping off on the molding machine as well to facilitate the suction of the damp cushion during the final pressing.

The polyelectrolyte added to the pulp consists of a polyacrylamide or cationic starch in the form of a solution.

The amount of polyelectrolyte added to the pulp is of the order of 1%, based on the dry fibers.

The water coming from the hot press is filtered through a sieve and then combined with the water coming from the molding machine comes, the combined water being used to carry out the various process stages.

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On the metal sieves and the metal sheets, which are used for pressing the Serving porridges, waxes are applied.

The method according to the invention can also be used to produce an insulating plate. In this case the fiber pad, which exits the molding machine, fed into a hot air dryer rather than a hot press.

The following example explains the invention without restricting it.

example

The result of the defibering of chips from a resinous wood in a defibering device and a steam pressure of 6 to The lignocellulosic fiber obtained at 12 bar is passed through by the steam at the outlet of the defibering device separated a cyclone.

In the cyclone, the fiber, which is at a dryness level of 65 to 70%, is added such an amount of circulating water that a slurry with a content of 3% dry fibers is obtained. While the dilution is being carried out, 0.015 to 0.1% of an antiseptic, based on the dry fibers, is added to the pulp to avoid fermentation. The pulp is then refined in conventional refiners. Lime and sodium aluminate are then added to the pulp in such amounts that the pH is maintained in the vicinity of 4 to 4.5, the amount of sodium aluminate added being such that 150 to 300 mg of Al ^ O ₃ are added per 100 g of the dry fibers will. The slurry treated in this way is treated again with circulating water to adjust its concentration to 1 to 2% of the dried material. Then the slurry is pumped into the distribution box of the molding machine. In this distribution box, 1%, based on the dry fibers, of a polyelectrolyte can then be added to the pulp, for example polyacrylamide or cationic starch in the form of a solution.

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solution to facilitate the release of water, the fiber pad After passing through the molding machine, it is cut to the desired length and placed in a hot press pressed under the usual conditions for the production of a hard board. To get the panels sticking to the metal screens as well To prevent the sheets that are used for pressing, are applied to these waxes.

The water emerging from the hot press is simply filtered through a sieve and then combined with the water that comes from the molding machine. The combined water is then used again to carry out the various stages of manufacture used.

The same procedure can be used to manufacture an insulation panel, except that the fiber padding is used by the molding machine leaves, is fed to a hot air dryer and not a hot press.

The method according to the invention therefore enables the total circulation of waters which are used in the production of panels from cellulosic fibers without the properties of these panels being influenced in the process. This method can be used in the same way in the production of cardboard boxes, if the pulp is produced on site by means of a defibering device. This method therefore makes a significant contribution to the fight against water pollution by those industries which use pulps made from lignocellulosic fibers. Furthermore, this method is more economical in view of the fact that the '· extracted from the wood during the defibering' and the refinement, which are usually removed with the used manufacturing water, can be reintroduced into the manufacturing cycle without the. Properties of the panels produced are affected ^{in a disadvantageous 1 way.}

The invention is not limited to the embodiments described above limited. All changes within the framework of

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the claims of the defined scope of protection are possible.

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Claims (1)

Claims 1. A process for the production of sheets of lignocellulosic fibers by wet means with total circulation of the production water, characterized in that the lignocellulosic fiber obtained by defibering wood chips in a defibering device under a water vapor pressure of 6 to 12 bar from the water vapor at the output of the defibering device in one Separator in which the solid phases are separated from the gaseous phase,
is separated in order to keep the temperature of the water consumed below 60 ° C, at the outlet of this separator Fiber, a certain amount of overflow water is added in the "total production" in such an amount, that a slurry with 3% dry fibers is obtained, then an antiseptic is added to the slurry, the slurry in the usual way In a manner refined, a neutralizing agent is then added if necessary to lower the pH to hold about 4 to 4.5, with the addition of the amount of aluminum ions necessary for gluing the panel it is necessary that the pulp treated in this way is then diluted again with overflow water in order to achieve its concentration adjust to 1 to 2% of solid dried matter, then put this pulp in the distribution box the molding machine, the fiber pad, after passing through this molding machine, in the desired Cut to length and pressed in a hot press under the usual conditions to obtain a hard board and all water resulting from these various measures is collected and recycled. 2. The method according to claim 1, characterized in that the separator in which the solid phases from the gaseous Phase be separated? which at the output of the defibering device is provided from a cyclone-like 4098 2 8/0 3 4-0 Separator exists. 3. The method according to claim 1, characterized in that the added to the slurry antiseptic product of chlorinated 'Phenols, such as sodium pentachlorophenate, formaldehyde or mercury derivatives. 4. The method according to claim 3, characterized in that the amount of the slurry added antiseptic between 0.015 and 0.1% based on the dry fibers. 5. The method according to claim 1, characterized in that the neutralizing agent to maintain the pH of the pulp close to 4 to 4.5 of lime and / or Natriuraaluminat consists. 6. The method according to claim 1, characterized in that the aluminum ions required for gluing the plate are added in the form of sodium aluminate, which is mixed in such an amount that 150 to 300 mg of Kl ^ Qs per 100 g of dry fibers are added. 7. The method according to claim 1, characterized in that the Slurry which is fed to the distribution box, small amounts of a polyelectrolyte to facilitate draining of the fiber pad on the molding machine and for vacuuming the damp pad during the final Compression can be added. 8. The method according to claim 1, characterized in that the polyelectrolyte added to the slurry consists of a polyacrylamide or a cationic starch in the form of a solution. 9. The method according to claim 8, characterized in that the amount of the slurry added polyelectrolyte in the Of the order of 1%, based on the dry fibers, lies. 409828/0340 TO, method according to one of the preceding claims, characterized characterized in that the water exiting the hot press is filtered by means of a sieve and then with the • pooling water coming from the molding machine, whereupon the combined waters again to carry out the different procedural stages can be used. 11. The method according to any one of the preceding claims, characterized in that waxes on the metal screens and the Sheets are applied, which are used to pre-press the pulp. - 12. The method according to any one of the preceding claims 1 to 11 ■ for the production of an insulating plate, characterized in that the fiber pad which leaves the molding machine, is fed to a hot air dryer rather than a hot press. "- 409828/0340