DE1113868B - Process for making paper stock from annual plants and stem plants such as bamboo and bagasse - Google Patents

Description

The invention relates to the production of paper stock by the known soda process. Thereafter, the raw material, which z. B. from wood chips, grasses, such as wheat straw, bagasse and / or bamboo, can be made, caustic soda added. The whole thing is on it during a Cooked time, which can vary from one to several hours and depends on the one used Temperature depends. The sodium hydroxide turns into a pulp in sodium carbonate when the raw material is converted converted. When the digestion is complete, the waste liquor is known as the black liquor is, and both various Na compounds, such as sodium carbonate, as well as something fresh Contains sodium hydroxide, deducted. The amount of unused sodium hydroxide is an average of 0.5% for straw, bagasse or other bulky raw materials and one considerably higher percentage of wood chips combined with stronger sodium hydroxide solutions to be cooked.

In the case of wood chips as a raw material, the black liquor not only contains a high percentage Sodium carbonate and other Na compounds, which are based on the strong concentration of the used Sodium hydroxide is based, but it is made by dissolving the wood pulp and the cellulose companion heavily enriched with organic matter. In fact, this happens so strongly that the ratio of Water to solids is about 2.5: 1, so it is advisable to convert the sodium compounds into sodium hydroxide to transform back. The black liquor is evaporated to such an extent that a black, viscous mass remains, which is too approximately equal parts of dissolved wood pulp and sodium compounds in addition to something free Sodium hydroxide and a small percentage of water. This mass is already easily flammable because of the wood pulp and pentosans that it contains and is used as fuel to evaporate more black liquor. The burnt viscous mass provides a soda containing soda Ash. To convert it back to sodium hydroxide, it is dissolved in water at 85 ° C and causticized by adding slaked lime, 90 to 95% of the sodium hydroxide can be recovered, but with a very large amount of equipment.

If the pulp is made from raw materials, their mass in relation to weight is great is larger than with wood (e.g. from grass, wheat straw and bagasse), weaker caustic soda becomes the Method of manufacture

of paper stock from annual plants

and stem plants such as bamboo and bagasse

Applicant:

Malise Graham Mackeurtan,
Durban, Natal (South African Union)

Representative: Dipl.-Ing. F.-W. Clodius, patent attorney,
Hamburg-Rahlstedt, Grubes Allee 26

Claimed priority:

South African Union August 24th

and October 11, 1956

Ernest Augustus Ritter,

Umhlanga Rocks, Natal (South African Union),
has been named as the inventor

Outcrop used. As a result, the ratio of water to solids in the waste liquor is high. At the Cooking grass is usually 8: 1 to 10: 1 for a well-digested, bleachable one Fabric and 12: 1 or more for a non-bleachable or coarse cardboard fabric. There is a lot of water must be evaporated, it is not economical to work with one of the usual soda furnace systems. The black liquor is then useless waste and a source of persistent serious disturbance.

The subject of the invention is a continuous reconversion of the sodium compounds into sodium hydroxide when breaking up grasses or similar raw materials with a weak sodium hydroxide solution, also the conversion of sodium carbonate to sodium hydroxide during the Digestion and its management in the cycle, the individual features of this combination being known should apply.

The term "grasses" is to be understood in the present case as any type of plant from which paper is usually used and which has a lower type weight than wood. So the term includes for example grass, straw, bamboo and especially bagasse.

According to the invention, the black liquor, the other sodium compounds and sodium hydroxide are used

109 688/54

3 4

in a ratio of at least 1; 4 contains, held by. Bagasse is fed through a feeder chute

Direct addition of lime, preferably burnt to the vat 1, and sodium hydroxide solution

Lime, causticized, whereby lime particles are fed into the cooker through an inlet pipe 4 into the vat 1,

If the bagasse is necessary for the following unlocking

To caustic cooker himself, and the process is taken up as the necessary amount of sodium hydroxide.

continuous process is carried out, when men has, it leaves the container 1 through a waste

where the raw material first enters a soaking river channel 5 and arrives in a sedimentation tank 6,

vat is brought, where it is for the following up- from where it is through a channel 7 into a standing

Finally absorb enough sodium hydroxide solution - cooker 8 is running.

can ren. The impregnated raw material is then treated with excess impregnation liquor, whose original

removed from the vat, then the Licher NaOH content of 1.5% now to about 1.0

The excess lye is withdrawn and then dropped to 0.9%.

Kocher directed where it is unlocked. The ab- ter 6 is drawn off and fed into a stirring vat 9,

Excess lye drawn is causticized by adding quicklime to it, namely in the

to which you add burnt lime directly and you 15 ratio of about 60 parts CaO to 100 parts

back into the soaking tub, while the len sodium carbonate that is in the excess

Digested raw material from the digester is located. The tub 9 is insulated

is removed. and provided with a wooden cover 10.

The black liquor, the other sodium compound, The caustic liquor runs out of the vat 9 in

gen and sodium hydroxide in a ratio of min- 20 a basin H ₁ from where they are pumped 12 in

at least 1: 4 can also be returned from the opened vat 1. It is important, that

raw material after its passage through the ratio of sodium carbonate to sodium

the cooker or the hydroxide withdrawn from the cooker itself in the impregnation solution in the vat 1

will. This black liquor will have to be at least 1: 4 before being recovered

burnt lime and then in 25 lye from the regeneration tub 9 into the tub 1

returned to the soaking tub. This black is headed.

Lye can be filtered to remove excess orga- As the impregnation lye, which is in regenerated form

To remove niche substance before it is fed back into the vat 1, quick lime

burnt lime is added. is added, it is clear that the bagasse that made

In addition, according to the invention, the vat 1 runs through 30 to the digester 8, with lime particles

an addition of barium chloride, resulting in dyes that serve to reduce the

Black liquor excreted before the regenerated sodium compounds held in the cooker itself too

Lye is returned to the soaking tub. To regenerate sodium hydroxide.

Basically, the present invention provides the After cooking, the bagasse runs from the combination of a per se known continuous digester 8 through a press screw 13 for further disintegration process with a treatment likewise in a known manner. The known exhaustion regeneration, in which the black liquor withdrawn from the screw 13, the conversion of the sodium compounds back into Na-NaOH content only about 0.6 to 0.5% under trium hydroxide takes place continuously. This process-corresponding increase in the proportion of soda ren has the advantage over the known individual processes 4 ° (Na ₂ CO ₃ ) and other Na compounds that it is carried out considerably more economically into a collecting basin 14, from where they are fed is because larger amounts of water can be evaporated into the regeneration tub 9 by means of a pump 15, which when weaker amounts are used through a pipe 16 which is obtained from a valve 17 via sodium hydroxide solution, is unnecessary. Opposite is known, can be directed. Excessive processes in which black liquor from the basin of the sedimentation tank 6 is causticized by the digester while the black liquor is flowing through the digester can also be conducted into basin 14,
follows, the extraordinarily essential advantage. The described method can be applied who achieves that it is not necessary to make special additives when cooking, when it comes to low-quality cellulose, which in turn delts the delt. For high quality fabrics, however, it is necessary to disrupt the cooking process. Nevertheless, the black liquor from the digester 8 offers another advantage of the new process that it can also be subjected to treatment during treatment.

Caustication of the black during the cooking process is therefore preferred from the basin 14

Caustic can be done by lime particles, which are from a rotating suction filter 18, the excess

organic matter removed from the raw material from the soaking vessel in the cooker, in a regeneration

be carried. Furthermore, the result is passed through the 55 vat 19, which is provided with a steam jacket and

Combination process achieved uniformity of the provided with stirring blades 20. The temperature

The digestion process a significantly better loading in the vat 19 is kept at about 80 ° C,

quality of the paper stock produced. Quick lime in the ratio of about 60 parts

Below is a method of making lime to 100 parts of sodium carbonate, which is used in the

of paper pulp made from bagasse is available on the basis of drawings

gen described; in the drawings shows added. The regenerated black liquor is made from

Fig. 1 is a working diagram that derives the treatment of the vat 19 by a rotary

Represents bagasse in continuous flow, suction filter 21 guided and by means of a pump 22 in

Fig. 2 is a partial diagram showing the treatment of a collecting container 23, from where it left

Bagasse illustrated in one batch. 65 back to soaking tub 1 as required

According to FIG. 1, one can be pumped with a steam jacket.

See soaking tub 1 with stirring blades 2 from 2.5 to 7% barium can be allowed from the collecting tank 23. The temperature in the vat will be added to the coloring substance and chloride at 80 ° C

to excrete any remaining sodium carbonate. The exact amount of barium chloride used depends on the degree of cleaning required and the degree to which the regenerated black liquor is from the collection tank 23 is drained from. In this way you can achieve a clear lye that is special is suitable if you want to get high-quality white paper as the end product.

Fig. 2 shows either a closed or an open cooker 24 in which the bagasse in Batch is cooked. During the cooking process, the lye is constantly drawn from the lower part of the Kochers withdrawn and pumped back by means of a pump 25 in its upper part. Line 26, which conducts the liquor is tapped at 27, and part of the black liquor is being regenerated into a Mixing tub 28 passed, where it causticized by adding quick lime in the same way as before will. The regenerated black liquor is brought from the vat 28 into a basin 29. One pump 30 leads them back into the digester 24 through a line 31.

It can be seen that the process cannot begin; H. that the black liquor is not out of the pipe 26 may be drained until at least 20% of the original sodium hydroxide charge are consumed unless there is enough black liquor from a previous boil that represents a ratio of other sodium compounds to sodium hydroxide of at least 1: 4, the cooker 24 has been added at the start of cooking.

At the end of the boil, the black liquor is removed from the digester 24 by draining it and or or the cooked bagasse passes through a screw press.

This black liquor can then be filtered and regenerated by adding quick lime, color additions therefrom by barium chloride in the same way as in the method according to FIG. 1 be eliminated.

Claims (1)

PATENT CLAIMS: 35 40 weak caustic soda using lime, especially quick lime, regenerated waste liquor, characterized in that the raw material is continuously impregnated with a sufficient amount of caustic soda in a soaking vessel, the excess soaking liquor containing at least 1 part by weight of other sodium Contains compounds to 4 parts by weight of NaOH, causticed with quick lime in a vat in a known manner and returned to the soaking vessel, the impregnated raw material is poured into the cooker and opened, the cooked material is discharged and the black liquor with a content of at least 1 part by weight of others Na compounds also regenerated to 4 parts by weight of NaOH. 2. The method according to claim 1, characterized in that the black liquor is regenerated in a special caustic pot by the direct addition of quick lime and then fed to the soaking vessel. 3. The method according to claim 1 and 2, characterized in that black liquor is continuously withdrawn from the digester, causticized by direct addition of quick lime and fed back to the digester. 4. The method according to claim 1 to 3, characterized in that dark-colored impurities in the black liquor are precipitated by the addition of barium chloride and are eliminated before the regenerated black liquor is recycled. 5. The method according to claim 1, characterized in that the black liquor is causticized in a manner known per se in the digester itself by lime particles which are carried along by the raw material from the soaking vessel into the digester. 1. Process for the production of paper stock from annual plants and stem plants, such as bamboo and bagasse, by digestion with publications under consideration:
German patent specifications No. 257124, 356 752, 396284, 591115, 747 236;
Paper Trade Journal, No. 33 of August 15, 1955, P. 30 to 1 sheet of drawings © 109 688/54 9.61