Pulping method with zero discharge of sewage water

Abstract

The invention discloses a pulp making method for discharging sewage thoroughly which includes the following steps: pulping material, steam cooking agent and catalyst are mixed evenly and put into a spherical digester and the mixture is cooked by steam; the cooked material is squeezed by passing through a plurality of twin-screw extruders connected in series so as to extract black liquid and obtain the pulp material, and the black liquid obtained from the last twin-screw extruder is squeezed sequentially after returning to the former twin-screw extruder, while the black liquid obtained from a first and a second twin-screw extruders is merged straightly, and the merged black liquid is concentrated and dried to obtain alkali lignin and or lignosulfonate; the pulp material is delivered into a twin-screw rubbing and kneading pulper, the polyester washing is carried out in multiple-section series while the pulp is grinded, or the polyester washing is carried out in multiple-section series and bleached in multiple-section series, the washing water is returned to the washing process in the former section, and finally the residuary black liquid is obtained, that is the washing water coming from the first washing process; then, the residuary black liquid is returned to the pulping material or the spherical digester; the pulp material is refined in a dual-disk refining machine by adding water, then a pulp plate is made after the refined pulp material enters a paper machine. Meanwhile, the removed water circulates to the dual-disk refining machine or other processes needing the water by the pure water treatment.

Description

technical field

[0001] The invention belongs to the technical field of papermaking and pulping, and in particular relates to a technology for making the pulping process without sewage discharge. Background technique

[0002] After alkaline pulping, a large amount of fiber and non-fiber raw materials and most of the alkaline substances are dissolved in the cooking liquid to become black liquor, which is the largest pollution source in the paper industry, and the pollution load can reach 90% of the total pollution load. At present, large-scale papermaking enterprises at home and abroad mostly use traditional alkali recovery technology to treat black liquor. This technology is more effective in reducing environmental pollution caused by the paper industry. However, the one-time investment of traditional alkali recovery technology is huge, and it generally takes The investment is tens of millions of yuan, and the daily operating costs are quite high. Therefore, many small and med...

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