SU834284A1 - Digesting liquid for double-stage acid-alkali delignification of cellulose-containing raw material - Google Patents

Description

(54) COOKING LIQUID FOR TWO-PERFORMED OXYGEN-LICORARY DELIGNIFICATION OF CELLULOSE-CONTAINING RAW MATERIALS

in the following ratio of components, mol.%:

Alkaline solution1-6

Spent liquor from the first stage delignification 26-34

Waste liquor from the second stage of dengnification60-72

The cooking liquid is prepared as follows.

The cellulose-containing raw materials and fresh alkaline solution for the first step of lignification are directed to the first step of delignification, carried out at high temperature and pressure. The resulting intermediate product, together with the spent alkaline solution, is directed to grinding, carried out at the pressure and temperature of cooking;

To carry out the second stage of celignification, carried out in the presence of an oxygen-containing gas, to the spent liquor remaining in the intermediate product from the first stage in the amount of 26-34 mol.% Add the spent liquor from the second stage delignification 60-72 mol.% And fresh alkaline solution 1 -6 mol.%.

The high quality of the delignified material obtained from the use of cooking liquid is largely due to the inhibitory capacity of the organic components contained in the spent liquors.

The introduction of an alkaline solution provides the desired pH value (9.0-10.0 throughout the entire delignification process, which is necessary to retain the high molecular weight fraction of organic substances inhibiting the delignification process in the right phase, and also provides for a more efficient delignification process due to the introduction of active alkali.

Example 1 A cooking liquid consisting of a mixture, mol%, is used for the experiments:

Waste liquor from

the first stage of delignification with residual

alkalinity of 9.2 g / l,

pH - 10,926

Spent liquor

from the second stage

delignificacin with residual alkalinity of 3.2 g / l, pH - 9.272

Alkaline solution containing Na and O2

With this cooking liquid, a two-stage oxygen-base delignification of cellulose-containing raw materials is carried out under laboratory conditions.

The experiments were carried out in glasses of acid-resistant steel. Glasses with an alkaline solution are heated in a glycerin bath at 170 ° C for 25 minutes. with a chemical consumption of 9.0 per unit. N.

This is followed by grinding and second delignification steps in the presence of oxygen-containing gas in a rotating autoclave using the above cooking liquid at 120 ° C, gas pressure of 10 atm for 45 minutes.

Example 2. A mixture of spent liquor from the first stage of delignification, spent liquor from the second stage of delignification and alkaline solution in a ratio (mol%) of 34: 65: 1, respectively, is used as a cooking liquid.

The content of residual alkalinity in solutions is similar to the example. one.

The delignification process is carried out as in Example 1,

Example 3. The delignification process is carried out analogously to example 1 with the following ratio of components of cooking liquid (mol.%) 34: 60: 6, respectively.

Example 4. The first stage of delignification was carried out under industrial conditions in a Pandy continuous apparatus. Dalu & e follows the grinding and second stage of delignification in a 400 L reactor with an oxygen-containing gas. The ratio of components of the cooking fluid (mol% 26: 68: 6, respectively.

Example 5. The process of delignification using cooking liquor is carried out as in Example 4, with the following ratio of components in solution (mol%) 22: 72: 6, respectively.

The quality indicators of the delignified material obtained in comparison with the known are given in the table.

Claims (1)

Claim . The cooking liquid for the two-stage oxygen-alkaline delignification of cellulose-containing raw materials, mainly for the second stage of delignification, containing an alkaline solution and spent liquor, different heme, which, in order to improve the quality of the delignified material and the conditions for the regeneration of the spent solution, it contains spent liquor a mixture of spent liquor from the first stage of delignification with a residual alkalinity of 0.9-1% in units NAD and spent liquor from the second stage of delignification with residual alkalinity of 0.3-0.4% in units Na ^ O in the following ratio of components, mol.%: Alkaline solution 1-6; spent liquor from the first stage of delignification 26-34 and spent liquor from the second stage of delignification 60-72.