DE1013956B - Process for the production of water-soluble, low-sulfur lignosulfo acids and their alkali or ammonium salts - Google Patents

Description

Process for the production of water-soluble, low-sulfur lignosulfonic acids and their alkali or. Ammonium salts It is known to use sulphite waste liquor under pressure To dissolve quick lime and then to treat with hydrochloric acid, whereby water-insoluble Products are obtained or, if an S: ulfite waste liquor after the alkali: i'hydroxydaufsc Inclusion was used, water-soluble products, but which have the same sulfur content like the starting products. It is further known to use sodium sulfite waste liquor Lime at temperatures below 100 ° and then with sulfuric acid or another strong one To treat acid or sodium bisulfate.

It has now been found that in the manufacture of pulp after the calcium bisulfite digestion resulting sulfite waste liquor, the lignin substance in a form that is valuable for further processing is obtained by using the sulphite waste liquor heated with calcium oxide or calcium hydroxide at temperatures up to the boiling point -and then subsequently by acidification and addition of alkali chloride or ammonium chloride the lignin substance precipitates. By then separating the precipitate from the Salting-out broth and about three to five-point washing with about 200/1) alkali or ammonium chloride solution, which can be acidified with a little hydrochloric acid the residue practically free of lime.

The applied calcium oxide can be used as quick lime, slaked lime, Calci, umhydroxyd or Kalkinilch can be used. The amount of calcium oxide or -hydroxyds can fluctuate within wide limits. The lower limit is expediently used so much that at the end of the perforation there is still a small excess of @ unverbrau.chlein Calcium hydroxide is present. There is no upper limit to the amount of lime that can be used. However, it is useful for practical reasons, not the amount of lime over about 501) / o, calculated on the dry substance of the sulphite to be treated. to choose, as otherwise the consumption of hydrochloric acid is disproportionately high.

In the process, one can assume both a sulfite blue.ge, as it is obtained in the known wood pulping process, but it can also be used ferment beforehand and distill off the fuel produced in this way. Concentration also plays a role the sulphite waste liquor does not play a fundamental role in the course of the reaction; one can thus according to the respective economic circumstances both of the accruing Assume thin caustic as well as caustic of 34 ° Be. Only the yield of lignin-containing Substance is higher when working with the concentrated sulphite waste liquor.

Those isolated from sulphite caustic can also be isolated in the same way Treat lignin sulfonic acid or its salts. The sulphite waste liquor can also be used derive from both deciduous and coniferous wood digestion.

Through the process described, the methoxyl groups in the lignin molecule not split. Only a part of the sulfo groups of the lignin sulfonic acid molecule is split off, depending on the test conditions up to over half of the originally existing. The lime content of the end product depends on the degree of Wash off. In general, the following is achieved: washing three to five times with Saline or amniotic chloride solution has a content of 0.1 to 0.3% Ca0. For some For further processing purposes it is recommended to postprecipitate the lignin substance Addition of an aryl-formaldehyde resin produced by a known process.

Example 1 1,375 parts of an unfermented sulphite blue: ge of 20 ° Be (with about 7.51) / o S and about 8 ° / o C H3 with 70 parts: quicklime 2 Heated to 1.00 ° for hours. The mixture is then acidified with 230 parts more concentrated, while stirring Hydrochloric acid at about 75 to 80 ° and the lignosulfonic acid compound falls through Addition of 300 parts of potassium chloride is complete. The precipitate is filtered off with suction and washed free of lime with 18% potassium chloride solution.

Yield: 310 parts of paste with 52.11) / o dry content (with 3.751) / o S and 8.4% O C H3 in the dry matter).

Example 2 2140 parts of unfermented sulphite waste liquor from 6 ° Be are with 33 parts quicklime heated to 98 ° for 4 hours and then at 80 ° with 138 parts of concentrated hydrochloric acid and 240 parts of rock salt containing the li, gninsulfosäurehaltige Connection failed. The paste is sucked and stirred three times and subsequent suction filtration with the same amount by weight of 25% saline solution and then washed 20% ammonium chloride solution lime-free.

Yield: 153 parts paste with 51.8% dry content (3.5% S and 8.4% OCH3 in the dry matter). Example 3 (comparative experiment without the addition of a salt) 1400 parts of sulphite waste liquor of 31 ° Be are boiled with 76 parts of calcium oxide for 5 hours and then precipitated at 85 ° with 450 parts of concentrated hydrochloric acid at 50 °. After suction filtering, the paste is washed free of lime with about 18% hydrochloric acid.

Yield: 6120 parts with 42.1% dry content (with 5.95% S and 12.6% O C H3 on dry matter).

Example 4 2000 parts of sulphite waste liquor of 20 ° Be are with it for 2 hours 130 parts of slaked lime heated to 98 ° and then. at 100 ° with 340 parts more concentrated Hydrochloric acid; and 460 parts of rock salt salted out. The reaction product falls as Kneadable resin and is kneaded three times with i.00 ° hotter 20% i, ger Saline solution, which has been acidified a little with hydrochloric acid, washed free of lime.

Yield: 325 parts with 75.4% dry matter and 3; 6% S and 8.35 "/ o OCH3 on dry matter. Example 5 1500 parts of beechwood sulphite waste liquor (concentration 32.8%; 7.4% OCH3 and 6.350% S on dry) with 99 parts quick lime for 5 hours heated to 98 to 100 ° and then with 475 parts of concentrated hydrochloric acid and 150 parts of table salt precipitated. The precipitate is with 20% saline solution, which is weakly acidified with hydrochloric acid, washed out until practically free of limescale.

Yield: 435 parts with a dry content of 55% and 2.43% S and 11.1% O C H3, based on dry substance.

Example 6 2000 parts of unfermented sulphite liquor which has been freed from fuel from 20 ° B8 with 55 parts quick lime in a closed stirred autoclave for 5 hours heated to 120 ° and then with 230 parts of concentrated hydrochloric acid and 170 Share table salt salted out. The precipitate becomes weak by washing three times with Acidified 200 / aiger saline solution washed free of lime.

Yield: 655 parts of a 46.7% paste, which is in the dry matter Contains 3.54% S and 9.05% OCH3. Example 7 3440 parts fermented and freed from fuel Sulfite. waste liquor of 20 ° Be (with 7.4% S and 8.0% OCH3 in the dry matter) heated to 98 ° for 2 hours with 350 parts of quick lime. Then stir in the mass 180 parts of a moist cresol-formaldehyde resin, which you through 6 hours of heating 90 parts of Kresol DAB 4, 40 parts of water, 0.45 parts of concentrated Sulfuric acid and 45 parts of 30% formaldehyde and stripping off the supernatant aqueous Receives liquid.

After thorough stirring, 875 parts of concentrated hydrochloric acid are run in and then add 350 parts of table salt. As a result, a dense, finely powdered one falls Precipitation from, sucked off and on the suction filter three to four times with a 20% ammonia solution, which contains about 3% hydrochloric acid, is washed free of lime.

Yield: 1300 parts of a 51.60 / yr paste of low-sulfur lignosulfonic acid Ammonium, which contains 3.78 "/ o S and 8.75% O CH in the dry matter.

Claims (1)

PATENT CLAIM: Process for the production of water-soluble, low-sulfur lignin sulfonic acids and their alkali metal or ammonium salts from aqueous calcium bisulfite pulp ablau @ ge heated with calcium oxide or hydroxide without pressure, characterized in that the lignosulfonic acid with aqueous hydrohalic acid and alkali - or ammonium halides is precipitated. Documents considered: German Patent No. 67,889; French patents nos. 39 929 (addition to patents nos. 628 775), 879113, 881 845.