Method for extracting and separating lignin from cooking liquid of caustic soda pulping

A technology of caustic soda pulping and cooking liquor, which is applied in the directions of pulping with inorganic alkali, pulping with cellulose raw materials, pulping with acid salt/acid anhydride, etc. The effect of simple processing equipment and short processing time

Inactive Publication Date: 2018-12-07
JINING MING SHENG NEW MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Aiming at the defects existing in the prior art, the present invention aims to improve the output, quality and efficiency of lignin products produced by the resource utilization of caustic soda

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] 10 kg of caustic soda pulping cooking liquid (5 degrees Baume, pH 12, density 1.019 g / ml, lignin content 3.13%) provided by the paper mill was left to settle for 4 hours. Another preparation: 1g polyacrylamide (concentration 90%, molecular weight 8 million, anion concentration 30%) was dissolved in 100g water, 1g polyaluminum chloride (Henan Ousheng Chemical Products Co., Ltd., 99%) was dissolved in 20g water.

[0038] The caustic soda pulping cooking liquid is pumped into the reaction kettle, and the liquefied SO 2 Lower the pH of the cooking liquid for pulping by the caustic soda method to 5.5 for the first time, then lower the pH of the cooking liquid for pulping by the caustic soda method to 3.0 again with a mixed solution of sulfuric acid and sodium bisulfate; to 85°C, keep it warm for 3.0h, then lower the temperature to 25°C to precipitate lignin; centrifuge, filter, and take the filter cake to obtain 309g of lignin with a content of 98% and an extraction rate of ...

Embodiment 2

[0041] 10 kg of caustic soda pulping cooking liquid (6 degrees Baume, pH 12.9, density 1.021 g / ml, lignin content 3.21%) provided by the paper mill was left to settle for 4 hours. Another preparation: 1g polyacrylamide (concentration 90%, molecular weight 8 million, anion concentration 30%) was dissolved in 100g water, 1g polyaluminum chloride (Henan Ousheng Chemical Products Co., Ltd., 99%) was dissolved in 20g water.

[0042] The soda pulping cooking liquid is pumped into the reaction kettle, the pH of the caustic soda pulping cooking liquid is firstly reduced to 4.5 with the flue gas from burning sulfur ore, and then the pH of the caustic soda pulping cooking liquid is lowered again with 93% sulfuric acid to 2.5; add flocculant aqueous solution and coagulant aqueous solution, stir well, heat to 95°C, keep warm for 4.0h, then cool down to 30°C to precipitate lignin; centrifuge, filter, and take filter cake to obtain 321g lignin, Content 98%, extraction rate 96%.

[0043] Ta...

Embodiment 3

[0045] 12 kg of caustic soda pulping cooking liquid (5 degrees Baume, pH 11, density 1.017 g / ml, lignin content 3.07%) provided by the paper mill was left to settle for 4 hours. Another preparation: 1g polyacrylamide (concentration 90%, molecular weight 8 million, anion concentration 30%) was dissolved in 100g water, 1g polyaluminum chloride (Henan Ousheng Chemical Products Co., Ltd., 99%) was dissolved in 20g water.

[0046] The soda pulping cooking liquid is pumped into the reaction kettle, the pH of the caustic soda pulping cooking liquid is firstly reduced to 5.0 with the flue gas from the incineration of sulfur ore, and then the pH of the caustic soda pulping cooking liquid is lowered again with a mixed solution of sulfuric acid and sodium bisulfate. The pH of the cooking liquid is 2.0; add flocculant aqueous solution and coagulant aqueous solution, stir well, heat to 90°C, keep warm for 4.0h, then cool down to 25°C to precipitate lignin; centrifuge, filter, and take filte...

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PUM

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Abstract

The invention provides a method for extracting and separating lignin from a cooking liquid of caustic soda pulping. The method comprises the following steps: carrying out standing on a cooking liquidof caustic soda pulping for 4-6 hours to settle impurities; adding flue gas of sulfur ore incineration or liquefied sulfur dioxide, and reducing the pH value of the cooking liquid of caustic soda pulping to 4.5-6.5 for a first time; adding sulfuric acid or a mixed solution of sulfuric acid and sodium hydrogen sulfate, and reducing the pH value of the cooking liquid of caustic soda pulping to 1.5-3.5 for a second time; and then adding a flocculant water solution and a coagulant aid water solution, fully carrying out stirring, carrying out heating, preserving heat, carrying out cooling to separate out lignin, and finally carrying out centrifugal separation to obtain the lignin. Through the implementation of the method, the one-time extraction rate of lignin is remarkably improved to 95% or above, and the highest extraction rate can be up to 98%. In addition, the method is simple to operate, is low in investment cost, is beneficial to environmental protection, and thus has a wide application prospect.

Description

technical field [0001] The invention belongs to the technical field of pulping, papermaking and biomass materials, and in particular relates to a method for extracting and separating lignin from pulping and cooking liquor by caustic soda method. Background technique [0002] The paper industry is an important traditional pillar industry in my country. At the same time, the paper industry is also an industry that consumes a lot of industrial energy and resources and causes serious pollution. According to the data of China's environmental department in 2007: the discharge of the paper industry is 3.18 billion cubic meters, accounting for 18.4% of the total industrial discharge in the country; the COD discharge is 1.526 million tons, accounting for 29.8% of the total discharge of the country. Among them, lignin in cooking liquid is one of the main factors causing pollution. [0003] Lignin is a kind of substance composed of polymerized aromatic alcohols, which exists in woody ...

Claims

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Application Information

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IPC IPC(8): D21C5/00D21C3/02D21C3/04D21C3/12
CPCD21C3/022D21C3/04D21C3/12D21C5/00
Inventor 施晓旦李赛邵威
Owner JINING MING SHENG NEW MATERIALS CO LTD
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