A pretreatment process for cooking black liquor in the recovery of pulp by diffusion dialysis

Abstract

The invention relates to a preprocessing technology for black liquor in diffusion dialysis recycling pulp manufacture, and belongs to the technical field of pulp manufacture. The preprocessing method comprises the following steps: adding flocculant into the black liquor, which contains sodium hydroxide with the concentration of 8-30 g / L, for flocculation, and keeping the concentration of the flocculant at 5-10 mg / L; filtering through a sheet frame filter with the bore diameter of 1,100-1,300 g / m<2>; then filtering through an ultrafiltration membrane with the bore diameter of 20-1,000 angstroms to reduce the concentration of large particle impurity; recycling lignin to obtain the preprocessing liquid used for diffusion dialysis treating for a cation exchange membrane. Through adopting specific preprocessing method to process the black liquor before entering the diffusion dialysis process, the preprocessing method can increase the recovery rate of alkali and hemicelluloses in the black liquor, reduce damage to the diffusion dialysis membrane system caused by the alkali liquid, prevent blockage of the diffusion dialysis membrane, prolong the service life of the membrane, and guarantee the smooth progress of diffusion dialysis and follow-up handling.

Description

technical field [0001] The invention relates to a material treatment process in chemical production. More specifically, the invention relates to a pretreatment process for cooking black liquor in pulp production recovered by diffusion dialysis, which belongs to the technical field of pulp production. Background technique [0002] In the viscose fiber production process in the chemical fiber industry, an alkaline liquid containing a high concentration of organic matter (mainly hemicellulose) will be produced. If it is allowed to be discharged directly, it will cause serious environmental pollution. If the lye is treated by neutralization, a large amount of acid will be consumed, and a large amount of inorganic salt will be formed in the lye, so the alkali in the lye is recovered, and the organic matter in it can be harmless Disposal of solid matter is a more environmentally friendly disposal method. [0003] In the process of pulping, the cotton linters are cooked with a st...

AI Technical Summary

Problems solved by technology

[0018] The present invention aims to solve the existing problems and defects of the existing diffusion dialysis technology for cooking black liquor used in the production of recovered pulp, and provides a pretreatment process for cooking black liquor in the production of recycled pulp by diffusion dialysis. In the cation exchange membrane diffusion dialysis process of cooking black liquor in the recovery of pulp manufacturing, a specific pretreatment method is used to treat the cooking black liquor with specific indicators to reduce the COD value, and then enter the cation exchange membrane to diffuse after obtaining a suitable pretreatment liquid During the dialysis process, improve the recovery rate and recovery of alkali and hemicellulose in the cooking black liquor, reduce the damage of alkali solution to the diffusion dialysis membrane system, improve the service life of the membrane, and ensure the smooth progress of diffusion dialysis and subsequent processes

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