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Processing method of paper-making pulping black liquor

A papermaking pulping black liquor and treatment method technology, which is applied in the chemical industry, can solve the problems of small treatment volume, large amount of resin consumption, and difficult separation operation, and achieve the effects of low cost, wide applicability, and simple process

Inactive Publication Date: 2011-09-14
张仲伦
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the alkali recovery method for processing black liquor has huge investment, high maintenance and operation costs, and the combustion process causes the emission of greenhouse gas carbon dioxide and produces a large amount of secondary pollutants—white mud; the purity of lignin separated by acid analysis is low, and waste Acid is easy to cause secondary pollution. When the precipitated lignin particles are small, especially when there is interference from silica gel in straw pulp, reed pulp, and bagasse pulp, it is difficult to wash, filter, and separate lignin; Lignin has the disadvantages of introducing impurities (flocculant), large amount of resin, loose lignin precipitation, and difficult separation operation; membrane separation method has the disadvantages of small water flux, low retention rate, small processing capacity, chroma, CODcr, BOD 5 The removal rate still needs to be improved; the biological method is generally only suitable for the treatment of CODcr and BOD 5 Relatively low dilute black liquor, high operating costs, strict operating conditions, and available lignin, polysaccharides and other organic substances are basically biochemically decomposed, and resources cannot be effectively utilized

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] The concentrated bagasse black liquor with a standard Baume degree of 28Be° has a solid content of 41.5%, wherein the lignin content is 12%, the inorganic matter is 14%, the polysaccharide is 15.9%, the pH value is 13.4, and the COD cr The value is 440000mg / l, BOD 5 The value is 125200mg / l (PH value, COD cr 、BOD 5 All were measured after 100-fold dilution). 37% industrial formaldehyde was added according to the molar ratio of lignin and formaldehyde of 1:1, and reacted at 80°C for 3 hours. The rotation speed of the stirring motor was 17 rpm, and the formaldehyde was added dropwise at a constant speed after the heating started, and the dropwise addition was completed within 1.5 hours.

[0019] Add sulfuric acid with a concentration of 38% to the black liquor after the polycondensation reaction until the pH value drops to 3, so that the lignin in the black liquor is precipitated to form a lignin suspension. Add sulfuric acid at a constant speed within 1 hour, and the ...

Embodiment 2

[0025] The concentrated wood pulp black liquor with a standard Baume degree of 18Be° has a solid content of 26.3%, wherein the lignin content is 8.1%, the inorganic matter is 8.0%, the polysaccharide is 10.2%, the pH value is 13.2, and the COD cr The value is 290000mg / l, BOD 5 The value is 82100mg / l (PH value, COD cr 、BOD 5 All were measured after 100-fold dilution). 37% industrial formaldehyde was added according to the molar ratio of lignin to formaldehyde of 1:0.1, and reacted at 70° C. for 4 hours. The rotation speed of the stirring motor was 17 rpm, and the formaldehyde was added dropwise at a constant speed after the heating started, and the dropwise addition was completed within 2 hours.

[0026] Introduce CO into the black liquor after polycondensation reaction 2 flue gas until the pH drops to 6. The lignin suspension was aged at about 50°C for 1 hour, and then left to stand for 12 hours. The lignin in the black liquor is precipitated to form a suspension of lign...

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Abstract

The invention discloses a processing method of paper-making pulping black liquor, and the method comprises polycondensation, acid precipitation, aging, precipitation, solid-liquid separation and drying of the pulping paper-making black liquor, and in the black liquor, the solid phase which mainly comprises lignin and the liquid phase which mainly comprises sodium salt solution are separated; and the Baume degree of the black liquor is larger than or equal to 15 Be degrees. The method has simple process, low cost and wide application range. The obtained lignin can be used as multiple industrial and agricultural raw materials; the chroma, CODcr and BOD5 of the obtained liquid phase are greatly reduced.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for treating papermaking pulping black liquor. Background technique [0002] The plant raw materials used for papermaking are mainly composed of cellulose, lignin and polysaccharides, among which cellulose is the effective component of papermaking, accounting for about 40% of the plant raw materials; lignin and polysaccharides account for about 60% of the plant raw materials. %, is separated to form waste liquid in the paper pulping process. The papermaking waste liquor formed by alkaline pulping is black liquor, which includes separated lignin, polysaccharides, residual alkali and water. The CODcr concentration of black liquor from different plant sources is between 15,000-500,000 mg / L, and lignin and its degradation products account for about 50% of the total CODcr. If the black liquor is discharged directly without effective treatment, it will not only seriously pol...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): D21C11/04
Inventor 张仲伦何孟群
Owner 张仲伦