Green bleaching method of sulfate bagasse slurry

Abstract

The invention belongs to the technical field of pulping papermaking, and relates to an efficient green sulfate bagasse slurry bleaching method. The bleaching method comprises: (1) pretreatment with an acid or a chelating agent; (2) bleaching with ozone; and (3) bleaching with hydrogen peroxide. According to the present invention, the bleaching method completely adopts the oxygen-containing bleaching agent to replace the traditional chlorine-containing bleaching agent, such that the generation and the emission of the adsorbable organic chloride are completely eliminated, the clean production of the green bleaching of the sulfate bagasse slurry is achieved, and characteristics of environmental protection and health on human are provided; the use amount of the clear water is saved by more than 50-80% compared with the existing bleaching method; compared with the construction investment of the same scale bleaching adopting chlorine dioxide, the construction investment of the bleaching method of the present invention can be saved by 30-50%; compared with the production cost of per ton of the slurry of the bleaching adopting chlorine dioxide, the production cost of per ton of the slurry of the bleaching method of the present invention can be saved by 300-500 yuan; and the obtained bleached sulfate bagasse slurry has the good quality, wherein the whiteness achieves more than 83% ISO, the viscosity achieves more than 550-600 ml / g, and the obtained bleached sulfate bagasse slurry is especially for papermaking the high-end and sanitary household paper.

Description

technical field [0001] The invention belongs to the technical field of pulping and papermaking technology, and in particular relates to an efficient and green kraft bagasse pulp bleaching method. Background technique [0002] Existing kraft bagasse pulp bleaching methods are mainly chlorine-containing bleaching processes, which specifically include two types of processes: bleaching processes containing elemental chlorine (ie, chlorine gas) and bleaching processes containing combined chlorine. The process contents of the two types of processes are as follows: [0003] 1. The bleaching process containing elemental chlorine (i.e. chlorine gas), the typical process includes: chlorination (C) - alkali treatment (E) - hypochlorite (H) bleaching (referred to as CEH bleaching, the same below), or Chlorination (C) - alkali treatment (E) - hypochlorite (H) - hypochlorite (H) bleaching (referred to as CEHH bleaching, the same below). CEH, CEHH bleaching process mainly has the followi...

AI Technical Summary

Problems solved by technology

[0004] (1) The process of chlorination and alkali treatment produces a large amount of carcinogenic toxic organic chloride (AOX). AOX not only exists in bleached wastewater, but also exists in kraft bagasse pulp and paper products, which is harmful to the environment and human health. cause great harm;

[0005] (2) The concentration of CEH and CEHH bleached kraft bagasse pulp is low, and the recycling of wastewater cannot be realized. The bleaching water consumption is large, and the wastewater discharge is also large, and the bleaching wastewater discharge is as high as 100-150m 3 / t slurry;

[0006] (3) COD of CEH and CEHH bleaching wastewater cr High, high AOX, unable to meet the requirements of the "Discharge Standard of Water Pollutants for Pulp and Paper Industry" (GB3544-2008);

[0007] (4) The whiteness of kraft bagasse pulp after bleaching is low (below 75% ISO), the paper becomes brittle, and the yellowing is serious, which cannot meet the papermaking requirements of high-grade industrial household paper;

[0010] (1) The chlorine dioxide preparation system is complicated, the operation risk is high, and the explosion limit concentration of chlorine dioxide in the air is low;

[0011] (2) Chlorine dioxide is extremely corrosive to bleaching equipment, and chlorine dioxide bleaching equipment requires strong corrosion resistance, and the investment in bleaching system equipment is huge;

[0012] (3) The production cost of chlorine dioxide is high, and the production cost of kraft bagasse pulp bleaching is large;

[0013] (4) The water consumption per ton of pulp in the bleaching system is large, and the wastewater discharge in the middle stage of bleaching is relatively large, generally 25-30m3 / t pulp;

[0014] (5) The pollution load of the wastewater in the middle section is relatively high, and the CODcr of the wastewater is 1100-1300mg / L;

[0015] (6) Toxic organic chlorides (AOX) are generated during the bleaching production process and enter into the middle-stage bleaching wastewater, causing serious harm to the environment and human health;

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