Chemi-mechanical pulp waste liquid alkaline recycling pretreatment method

Abstract

The invention discloses a chemi-mechanical pulp waste liquid alkaline recycling pretreatment method. The method comprises the following steps of: first, collectinga waste liquid in the chemi-mechanical pulp producing process into a waste liquid middle pool, wherein the middle pool is a square cement pool or a circular steel groove; placing the middle pool beside an extruder; and then feeding the waste liquid of the middle pool into a filtering device to be filtered; feeding the filtered waste slag into a slag screening pool; feeding a filter liquor into an alkaline recycling treatment procedure, wherein filtering device is a pressure screen, a fine grid or a conical slag separator; feeding the waste slag into a fluid exhaustion device to carry out fluid exhaustion; controlling the mass of the removed slag to be 70-90% of the total mass of the screen slag; and collecting the waste water after fluid exhaustion and feeding the waste water into the waste liquid middle pool, wherein the fluid exhaustion device is a filtering type centrifugal concentrator, a sedimentation type centrifugal concentrator or a spiral press master. According to the invention, the waste liquid is pre-treated before the alkaline is recycled so that the follow-up alkaline recycling efficiency is enhanced and greater environment friendliness is obtained.

Description

technical field [0001] The invention relates to the alkali recovery of chemical-mechanical pulp waste liquid in the field of pulping, in particular to a method for alkali recovery and pretreatment of chemical-mechanical pulp waste liquid. Background technique [0002] As a high-yield pulping method, chemical-mechanical pulp can effectively utilize fiber raw materials, and the raw material consumption and water consumption per ton of pulp are less than those of chemical pulp. Due to less water consumption, the content of inorganic substances such as carbohydrates, lignin, extracts and alkalis in wastewater is relatively high. Untreated wastewater is highly toxic to microorganisms in water bodies, which affects the biological treatment of wastewater. In order to protect the environment and save costs for the company, there are a series of pulping workshops such as alkali recovery. On the one hand, the waste water is treated to meet the requirements of environmental protection...

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Problems solved by technology

But this method filtrate A carries out evaporation, steam stripping treatment, and energy consumption is big

[0004] At present, the alkali recovery process of chemical and mechanical pulp is mainly to directly enter the collected waste liquid into the alkali recovery process. On the one hand, this method affects the efficiency of subsequent alkali recovery due to the mixing of many slags in the waste liquid; on the other hand, in In the production of chemical-mechanical pulp, a lot of slag is produced while the waste liquid is discharged. There is still a certain amount of waste liquid in the slag, and the residual waste liquid is also rich in alkali. If it is directly discharged, it will not only pollute the environment , and cause a waste of alkali

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