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Novel method for recycling straw pulp black liquid alkali through acid-base circulation

A technology of black liquor alkali and a new method, applied in the regeneration of alkali liquor, pulping with inorganic alkali, etc., can solve problems such as serious pollution, difficult black liquor treatment, and shortage of papermaking raw materials

Inactive Publication Date: 2020-12-04
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is mainly to solve the problems of non-wood pulping and papermaking black liquor, such as difficult treatment and serious pollution. cleaner production
On the one hand, it solves the shortage of raw materials for papermaking in my country, no longer relies on imported waste paper, and makes full use of local straw resources; on the other hand, based on the concept of biorefinery, the components of straw resources are separated, and the separated cellulose can not only be used for Pulping and papermaking can also be used to produce other cellulose products, lignin extracted from black liquor can be used to produce humic acid and other fertilizers

Method used

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  • Novel method for recycling straw pulp black liquid alkali through acid-base circulation
  • Novel method for recycling straw pulp black liquid alkali through acid-base circulation
  • Novel method for recycling straw pulp black liquid alkali through acid-base circulation

Examples

Experimental program
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Effect test

Embodiment 1

[0019] (1) Preparation of black liquor: cut the straw into 3cm, add it to the cooking pot, the solid-liquid ratio is 1:5 (mass ratio), and the cooking conditions are: the cooking alkali is NaOH, and the amount of alkali used accounts for the dry straw raw material 15% of the mass, the cooking temperature is 150°C, and the cooking time is 1.5h. After the cooking is completed, the obtained slurry is filtered, and the solid material is fully washed until the pH of the solid material is 6, and all the filtrate and washing liquid are collected to obtain the required black liquor;

[0020] (2) black liquor phosphoric acid treatment: add NH in the black liquor that step (1) obtains 4 h 2 PO 4 Adjust the pH to 5 to precipitate a part of lignin. After removing the precipitate by centrifugation, continue to add phosphoric acid to the supernatant to adjust the pH to less than 2. Centrifuge to obtain the extracted lignin and NaH 2 PO 4 red liquid;

[0021] (3)NaH 2 PO 4 The caustic...

Embodiment 2

[0025] (1) Preparation of black liquor: cut the straw into 5cm, put it into the cooking pot, the solid-liquid ratio is 1:6 (mass ratio), the cooking conditions are: the cooking alkali is NaOH, the amount of alkali used accounts for the dry straw raw material 20% of the mass, the cooking temperature is 160°C, and the cooking time is 2h. After the cooking is completed, the obtained slurry is filtered, and the solid material is fully washed until the pH of the solid material is 7, and all the filtrate and washing liquid are collected to obtain the required black liquor;

[0026] (2) black liquor phosphoric acid treatment: add NH in the black liquor that step (1) obtains 4 h 2 PO 4 Adjust the pH to 5 to precipitate a part of lignin. After removing the precipitate by centrifugation, continue to add phosphoric acid to the supernatant to adjust the pH to less than 2. Centrifuge to obtain the extracted lignin and NaH 2 PO 4 red liquid;

[0027] (3)NaH 2 PO 4 The causticization ...

Embodiment 3

[0031] (1) Preparation of black liquor: cut the straw into 10cm, add it to the cooking pot, the solid-liquid ratio is 1:7 (mass ratio), and the cooking conditions are: the cooking alkali is NaOH, and the amount of alkali used accounts for the dry straw raw material 25% of the mass, the cooking temperature is 170°C, and the cooking time is 3h. After the cooking is completed, the obtained slurry is filtered, and the solid material is fully washed until the pH of the solid material is 8, and all the filtrate and washing liquid are collected to obtain the required black liquor;

[0032] (2) black liquor phosphoric acid treatment: add NH in the black liquor that step (1) obtains 4 h 2 PO 4 Adjust the pH to 6 to precipitate a part of lignin. After removing the precipitate by centrifugation, continue to add phosphoric acid to the supernatant to adjust the pH to less than 2. Centrifuge to obtain the extracted lignin and NaH 2 PO 4 red liquid;

[0033] (3)NaH 2 PO 4 The caustici...

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Abstract

Aiming at the problem that the black liquor is difficult to evaporate and burn due to high silicon cell content and existence of sodium silicate in the existing straw pulp black liquor, the inventionprovides a novel method for recycling straw pulp black liquid alkali through acid-base circulation. According to the method, phosphoric acid is used as an acid precipitation solution, and lignin is deposited by adjusting the pH value of the black liquor, so that lignin is extracted from the black liquor. Phosphoric acid serves as a medium strong acid and can reach the pH required by complete deposition of lignin, sodium dihydrogen phosphate generated in filtrate is causticized with calcium hydroxide, products are calcium phosphate and sodium hydroxide, sodium hydroxide can serve as cooking white liquor to be recycled, and phosphoric acid and calcium hydroxide can be obtained through a phosphogypsum recycling way. Materials in the whole process are all recycled, harmful wastewater is not generated, and clean production of non-wood fiber pulping and papermaking can be truly achieved.

Description

technical field [0001] The invention belongs to a novel acid-base regeneration cycle alkali recovery method for papermaking black liquor, relates to the pollution control of straw pulp black liquor in alkaline pulping, and is especially suitable for the technological transformation of black liquor acid analysis method. Background technique [0002] The silicon cells of non-wood raw materials contain a large amount of silicon elements. During the traditional alkaline pulping and cooking process, the silicon cells are dissolved by the lye, and the silicon elements are dissolved in the form of sodium silicate and exist in the black liquor, resulting in black liquor viscosity. Increased, the black liquor extraction rate is low, and the subsequent alkali recovery and reuse of black liquor is difficult, which is the so-called "silicon interference problem". The lignin in the black liquor can produce degradable and renewable polymers, and hemicellulose can be used as a raw material...

Claims

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Application Information

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IPC IPC(8): D21C3/02D21C11/04
CPCD21C3/02D21C11/04
Inventor 王岚刘菲菲李佐虎陈洪章
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI