DE1692844A1 - Process for the production of semi-pulps and chemo-mechanical pulps - Google Patents

Description

DR. ING. H. NEGENpANK FAISNIAKIVALI } HA MB ü HG 3β NK IT KB W1L141 FKKNR Γ J ¹ 30 74 28 Ό S J> 38 41 13 TELEQH AMM-ASBOUKIFT I I

Defibrator Aktiebolag

Master Samuelsgatan 32 29 »March 1966

Stockholm 7 (Sweden)

Process for the production of half z express fabrics and, chemo-mechanical Pulps

The present invention comprises a process for the production of semi-pulps and chemo-mechanical pulps from lignocellulosic, plant-based raw material, such as deciduous and coniferous holy, straw and hay-like Bohstoff, extracted sugar cane residues, which alone or together with other a fiber material for the production of paper, cardboard, fiberboard and other products can be used *

Because of the increasingly strict conditions all over the world Legislation against water pollution is also related to the recovery of waste liquor and chemicals has become more and more up-to-date with these types of pulp, especially because it is often desirable From the point of view of raw material supply and transport, the pulp mills are far removed from the Seashore near water pollution sensitive To relocate wastewater receivers, such as inland lakes and rivers.

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The production of the types of pulp in question is mostly based on heating the vegetable raw material under pressure with a sodium sulfite solution, which, in addition to sodium sulfite, has one or more of the components sodium hydrogen sulfite »sodium hydrogen carbonate and Sodium carbonate may contain “chemical recovery is relatively cumbersome with sodium-based Koohung and expensive and therefore less suitable for small and even medium-sized factories. The majority of recovery methods is based on reducing combustion of the waste liquor thickened by concentration with the production of a so-called soda melt, which consists essentially of sodium sulfide and sodium carbonate. The transformation of the soda melt into sodium sulfite is the most cumbersome stage in the recovery process.

The disposal of the waste liquor is easier when cooking on an ammonium and magnesium basis * In both cases the waste liquor can be oxidatively burned · The ammonium waste liquors result in a small amount of plant ash and the Magnesium waste an ash rich in magnesium oxide. The contamination of the plant ash is also with recirculation so low that it is of no practical importance. Disadvantages b <u of ammonium sulphite boiling are that it does not appear to be is possible to make white pulps, and that both the ammonia as well as the sulfur are lost. The ammonia is burned to nitrogen and the sulfur to sulfur dioxide, the recovery of which from the flue gases by washing with ammonia causes difficulties · pulps of the here in The varieties in question are apparently not produced at all or only to a small extent on the basis of magnesium, what

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should be based on the fact that difficulties with the limited water solubility of magnesium sulfite at pH> about 4 are linked * The magnesium oxide ash is easy to get in Conversion of magnesium hydrogen sulfide into an aqueous suspension by reaction with sulfur dioxide «It is also possible that Scbefeldioxyd from the flue gases by washing with a aqueous suspension of fresh or regenerated t! agnesiuBioxyd win back. ■

The solubility of magnesium sulfite, HgSO ₅ · 6H ₂ O in cold water is about 12.5 g / l or 0.059 δ aol / 1 «Since the plant material when impregnated is generally between 0.5 and 1.5 l / kg of the impregnation solution aufnimat, an amount of sulfite required to carry out the cooking cannot be introduced into the starting material, primarily Hole, by impregnation with magnesium sulfite. On the other hand, this is possible when impregnated with magnesium hydrogen sulfite, which is very easily soluble in water at pH * or lower.

Impregnation at low pH results in rapid and high idgnine sulfonation, which triggers the lignina during of cooking promotes. On the other hand, in view of the paper properties of the pulp, it is desirable that the hydrolytic decomposition and disintegration of hemicellulosic components to be retained by cooking at pH values above 4. This also prevents the hydrogen sulfite from falling into thiosulfate, polythionate and SuI-at, connections that also go through :. the implementation between Sulphite and reducing and oxidizing atomic groups in the vegetable: aterial are formed, against. Through this

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Reaction, the cooking liquor gradually becomes poorer in buffering sulfite ions, which together with hydrolytic decomposition of acetyl groups and other acyl groups lead to a progressive lowering of the pE-Vertes during the cooking process β . The production of white cellulose requires a strong impregnation with sulfite and a high residual sulfite content at the end of the cooking process. An angel of sulfite results in more or less discolored cellulose.

If you are therefore due to the aforementioned or other causes the alignment of the vegetable material with a I want to run sulphite solution of pH 4 or lower, i ^ t it is desirable or even necessary to adjust the pH value in the impregnated material before or at the beginning of the cooking process to be able to increase

Taking into account the aspects listed here, a * magnesium sulfite process has been worked out according to the invention, which can be adapted to the production of both brown and white cellulose types from different types of vegetable starting material by making minor modifications. Bs is characterized in that the vegetable material eemäß methods known per se IAIT einor acidic IlagBaiumsulfitlösung impregnated, then at a temperature of about 10O ⁰ C, vorzuBweise about 15O ⁰ C, after or during ^ uuamiaenfuhrung with a water soluble Sticketoffverbinduno with neutralizing the pH heated under pressure to increase the effect and then subjected to mechanical fiberization and grinding according to methods known per se.

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As should be justified later in this or description, it can be advantageous in different crün-sen impregnation with a solution in certain cases, which apart from I faonesium hydrogen sulfite also ammonium hydrogen sulfite and / or contains free sulfur dioxide.

Special in the production of white wool types the Eest content of sulfite in the waste liquor is so high that it it is worth using for renewed impregnation and boiling after processing, av / ocknahmin; for one type of pulp, b3i vjelchor the anof.rucha are smaller in brightness, e.g. for ao-r. "oorrurating" pulp. The Kochlau ^ o v / ird here In addition to the organic substances, there are also organic substances

, Polythionate, sulfate and acetate that contain and the nitrogen base used are bound. As a neutralizing Otickotoffvereinigung kani> nian ammonia, Αί-ino, some ariids and 3alts this connection with weak ones Or use strong G; -uren. Because of economical reasons However, they can hardly be more than ammonia, ammonium sulfide and urea (Carbamide) into consideration. When heating the material impregnated with the acidic agnesiumsulfite solution dissociate the compounds sulphite - ionon? -e / a according to the formula

2 HSOj H ₂ O ♦ SO ₂ + SOT

with the migration of the released sulfur dioxide to the surface of the labeled ^T atorlals, v / o it is neutralized by the nitrogen compound added after the impregnation. Infol & odeuisen oteiyt the pH value inside the material,

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what ssu a certain excretion and accumulation τοη Magnesium sulphite (MgSO,) can lead to the inner bearings of the material. By the aforementioned »lowering the pH value and sulfite consuming reactions, however, the excreted !. "en ^ e reduced again in the course of cooking! if not completely made to disappear

By making the impregnation with an ammonium hydrogen sulfite Magneeiuiawasseratoffsulfitlösung can if this should prove to be desirable in the production of e.g. white pulps, during the a higher soluble sulphite concentration throughout the cooking process maintain.

The use of free Aanaoniak as Heutralisationsinittel can local "relatively large increases the pH .ertes cause, which may reduce the brightness of the substance · it may Therefore, in the production of white pulps from raw materials which tend to discolor in alkaline solution It would be more advantageous to use ammonium sulphite as an IT neutralization agent, if necessary mixed with ammonium / aB s era tof f sulphite

The process of the invention can be used for batch as well as continuous cooking in both steam and Design the liquid phase appropriately · One for implementation The procedure that is well suited to the process can be built up from the following sub-operations *

a) steam treatment of the starting plant material,

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SAD GHiCiIwVu

b) Impregnation of the steamed material with acid Magnesium sulphite solution by, mechanically © zucamm pressing the dampened material and subsequent expansion under the Surface of the impregnation solution and deposition of excess impregnation solution z. B. by draining,

c) Introducing the impregnated material into the digester by means of a circulating conveyor or another "non-compressing device" after or during or before the addition of a neutralizing nitrogen compound, such as gaseous or caustic ammonia, ammonium sulfite or urea ₉

d) cooking with direct steam,

e) intermittent or continuous discharge of the material heated under pressure for the purpose of mechanical division of the applied material by defibration and Grinding in direct connection with the discharge or in one or more separate treatments in stages or complete pressure relief, temperature reduction and dilution.

The equipment required for this can be used in suitable Share according to the West German patent Kr. (Pat-Note! Tr. A 31 892 VI / 55b) trained 3ein,

The dampened "atorial" can be mechanically pressed in the roaction vessel sdttels a conical SchrauuQ eingotPatren and in one im in the stove expand the attached vessel and suck up the solution, see e.g. the West German patent Hr.

(Pat.Anm · Hp. D 4-3 217 VIb / 55b).

The damped or not damped material can also be used the displacement and / or diffusion principle at normal, reduced or increased pressure and at normal or increased pressure Temperature can be impregnated, and the impregnated © material can be put into the cooker by means of a conveyor or the like be registered · Such a procedure is e.B «in the West German patent Wr (Pat.Anm.! Tr. D # 9 281 / XVa / 55b) described

The impregnation can also be carried out according to the vacuum principle will·

If it is possible to recover the chemicals and / or to dispose of the waste liquor in such a way that it is ice in water can contaminate, the waste liquor is separated, concentrated, and / burned, after which the magnesium oxide ash obtained through Treatment with sulfur dioxide converted back into acid sulphite liquor will·

The following, carried out on a semi-technical laboratory scale Experiments shed light on the results that are obtainable in cooking carried out according to the invention.

Example 1·

(White fabric, 82% yield). Blrkenhol chunks, £ 600 absolute dry weight, were steamed for 15 minutes

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steamed, compressed in a hydraulic press to 140 kg / cm and then left to expand freely in 5000 ml of a 60 ⁰ O warm magnesium / as ^ rstoffsulfitlÖsuag containing 30.2 g (0.80 mol) KgO / 1 and its pH> 4 , 0 v; ar. After three minutes the oil was not sucked up by the chopping sticks and deposited. 1000 ml had been drawn up (the relatively large amount is due to the fact that the corner pieces were relatively finely chopped). The amount of solution absorbed by 1 kg of dry wood was 1 »67 1» the amount of MgO thus 1.14 nol / kg »4.60 K» The chopped pieces were placed in a defibrator built for laboratory purposes, with 50 ml of 5 ~ Efol caustic ammonia "0.42 iaol per kg 'irockenholz" * 0.71 X poured over it and heated in direct steam for 20 minutes at 170 ⁰ O (7.2 atmospheres) Jiantel was led, had fallen to the lOeiaperatur in the Sboff to slightly below 100 ⁰ O, whereupon the material pulped wurd 30 seconds · iiach 5 "1E and 18 Liinutan and shredding was the pH in the pulp 5» 3y 5f2j 4.8 and 4.65. The fabric yield after washing was C2> £. The fabric was refined in a disc refiner, and sheets of paper were formed from it and tested. The sample results are summarized in Table 1.

BaiapJQl 2. (high yield substance of the "corrugating" type, harvest 88 #) · Chopped birch wood pieces, 700 g absolute dry weight, were impregnated as in Example 1 with a UagneaiumwascorstoffsulfitlüEung, the 16.4 ζ or 0, # 1 mol UgO / 1. and the pH of which was 4.0. The used HoI * -

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Etüoke were coarser, which is why only 1.29 liters of solution per kg of dry wood was absorbed, which corresponds to 0.53 mol / kg of dry wood or 2.15 % . The impregnated wooden pieces were poured over with 30 ml of 5 mol caustic ammonia = 0.21 mol / kg dry holi · 0.36 pounds. Coohing took place for 15 minutes up to 170 ° 0 · cooling, etc. as in Example 1. Five times 5 and 10 minutes and defibering ..ar the pH in the pulp 5.40, 4.85 and 4.40. The material yield «88; -. The sample results for paper sheets made from the pulp are compiled in Table 1.

Example 3 * (substance with a low yield of the "corrugating" type, yield 75 »3 pounds) · Impregnation of the same amount of wood with the same solution as in Example 2 · Double the small amount of 5 mol of ammonia was added. Amount of MgO absorbed 0.43 mol / kg dry hola _{· 1 t} 73 ύ Aiamoniak. * 0.42 molAg · Xdry wood * 0.72 Boiling 26 minutes at 170 ^Ö 0 · Cooling, defibration * and "further treatment as in example 1. pH - ". 7ert after 10 and 15 minutes as well as defibration · 4.5 \ 4.35 and 4.0 fabric yield 75.3 55.

The sample results for paper sheets made from the pulp are shown in Table 1

üGlopjel 4. (white material, yield 80.5 "A) . Chopsticks of fresh birch wood, 700 g absolute dry weight, were steamed and, as in liöisplel 1, impregnated with a liagnesiua ammonium tick sulfite solution, with a dioso solution 0.6 mol« 24.2 g of MgO, and 0 3 mol * ■ 5.1 g NR * ^Ρ ΘΓ liter at a pH -. 4.0 containing 0.96 Hole sucked X, ie 23 "2 g of MgO and 55.2 grams of sulfur per kg TrookenholB.

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BAD OrHGSNAL

The impregnated wood was in the defibrator with 75
5 laol! Faustian ammonia 7t3 S NEW / kg dry holi; poured over Total τ / urde IiH, · 15, 2 e / ^ B dry hola verv / ends. .. hole was made v / trend 50 lünutsn at 170 ⁰ O. Abüb-

^ and 2 er £ ac © rung v / ie in case 1. The pH- '. / ert after
10 lines and graining was 4.95 and 4 _t 5 fabric yield 80.5 X *

I ^ piorprobeersebnißso emerge from Table 1

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BAD OWGiNAL Table 1

example 1 20th 30th 2 20th 35.5 3 2) 31 59 4th MgO g / kg abs. dry. Hauls 53.6 557 352 20.7 530 527 17.3 2) 380 150 23.2 CWR It N 85.5 1.87 1.60 33.0 1.69 1.38 27.5 1.56 1.31 55.2 HH, «" "» 7.1 14th 24 5.6 22nd 37 7.2 29 42 12.2 ⁵ * Cooking time, minutes 20th 3473 5079 15th 5376 6841 26th 6644 8111 20th Cooking temperature, ⁰ C 170 2 _% 3 2.9 170 3 · 2 4.0 IT © 3 2 4 3 170 pH after defibration 4.65 64 • ^
78 4.4 •, ··
77 75 4.0 70 * »·,.?
68 4.5 Fabric yield,% 82.1 6th 18th 87.9 27 63 75.3 35 211 80.5 Paper sample results t 33 50 48 60 71 58 54 NMM
O SH ° degree of unit 44.5 34 47 63 D 43 48 48 63 47 58 OO 252 52 52 123 1) 46 46 193 46 61 57 JO Dimensions cmVg 1.29 1.27 239 245 1.29 270 228 ZD Explosive factor 46 42 43 Tear-off length b 7300 7772 7035 (JJ
aa 4 * 0 4.3 4- ¹ p Was Hot factor 78 73 65 Double folding (800 times) g 201 224 139 (MT hot 127 g / * ² Ib 45 49 70 69 CMT cond. ^N Ib 64 70 66 55 Brightness % CS 56 49 50 44 Opacity 187 214 209

1) 25% SH 20 ♦ 75 % SH 63 2

2) 25% SH 20 + 75 % SB 48 M

3) Of this, 4.9 g as ammonium hydrogen sulfite in connection with the ^. Impregnation and 7.3 g after impregnation as 5-mol chew. Ammonia "^

Claims (1)

Claims 1 · Process for the production of semi-pulps and chemo-mechanical pulps suitable for the production of paper, cardboard, fibreboard and similar products from lignocellulosic vegetable material, characterized . that the material is impregnated with an acidic magnesium sulphite solution, heated under pressure after or during the addition of a water-soluble nitrogen compound with a neutralizing, pH-increasing effect and then subjected to mechanical fiberization and / or grinding according to methods known per se. 2. The method according to claim 1, characterized . that the acidic magnesium sulfite solution contains not only magnesium sulfite but also ammonium hydrogen sulfite and / or free sulfur dioxide. 5. Process according to claims 1 and 2, characterized in that the acidic magnesium sulfite solution is made from recirculated waste liquor which is sulfite and possibly ammonium hydrogen sulfite and sulfur-109844/0298 • 2 * ORIGINAL BATHROOM 16028 ^ 4 the dioxide has been refreshed 4. Process according to Claims 1-3 » characterized in that the neutralizing nitrogen compound is ammonia, an amine, an amide or a salt of these bases with a weak or medium-strength acid, such as carbonic acid, sulfur dioxide and acetic acid. 5. Process according to claims i- ^ l-, characterized in that the neutralizing nitrogen compound is gaseous (liquid) or caustic ammonia or ammonium sulfite, possibly mixed with ammonium hydrogen sulfite, or urea (carbamide). 6. Method according to claims! 1-5 » characterized in that the heating of the impregnated material is carried out under pressure in the vapor phase at a ratio of dry material to liquid greater than 1i4 or 1i3 · 109844/0298