A kind of DMAC waste liquid processing method that spandex contains acetic acid

Abstract

The invention provides a treatment method for acetic acid-containing DMAc waste liquor of spandex. The treatment method comprises the following steps of: feeding acetic acid-containing DMAc waste liquor into a low-pressure tower, extracting a DMAc gas phase from the tower top of the low-pressure tower, feeding low-pressure mixed liquor which is formed by co-boiling acetic acid and DMAc at a towerkettle of the low-pressure tower into a high-pressure tower; extracting an acetic acid gas phase from the tower top of the high-pressure tower, and returning high-pressure mixed liquor which is formedby co-boiling acetic acid and the DMAc at the tower kettle of the high-pressure tower to the low-pressure tower. The treatment method has the characteristics of being simple in process, high in DMAcrecovery rate, low in treatment cost, and not adding a third component to guarantee cyclic use of the DMAc.

Description

Technical field [0001] The invention belongs to the technical field of industrial wastewater treatment, and specifically relates to a process method for the treatment of spandex DMAc waste liquid, which adopts a pressure swing distillation method to separate a mixed solvent of acetic acid and DMAc containing high polymer. Background technique [0002] In the spandex dry spinning process, three processes are mainly involved: polymerization, spinning and solvent recovery. Under normal circumstances, DMAc will be used as a solvent for polymer dispersion during the polymerization process, and after being separated and collected during the spinning process, it is sent to the solvent recovery device. In the solvent recovery process, most of the DMAc is recovered and recycled, and a small part of the mixed solvent of acetic acid and DMAc containing polymers will be treated as hazardous waste. With the improvement of environmental protection laws and regulations, the concept of green ch...

AI Technical Summary

Problems solved by technology

First, adopt the method of batch rectification, add the mixed solvent of DMAc and acetic acid containing high polymer to the distillation pot for rectification treatment, and obtain a part of the DMAc solvent with low acetic acid content at the top of the tower for recycling, most of which contain high polymer The mixed solvent of DMAc and acetic acid will be discharged at the bottom of the distillation tank as a hazardous waste, which causes a large amount of DMAc solvent to be lost and the yield is low; A certain amount of lye is added to the mixed solvent of acetic acid to neutralize the acetic acid in the mixed solvent, and then through simple distillation, water and DMAc are obtained at the top of the tower, and the bottom of the still is high polymer and sodium acetate and other salts. Although the process method can significantly improve the recovery rate of DMAc, it consumes a lot of steam, and additional lye needs to be added, and the produced sodium acetate and other salts are difficult to handle, which eventually leads to high recovery costs and is not economical.

The 3rd, be the combination of above-mentioned two kinds of techniques, still have the defective of above-mentioned two kinds of techniques

A method is by adding a third component, such as tetrachloroethylene, water, etc., to the DMAc and acetic acid system, and adopts azeotropic distillation to recover DMAc and acetic acid respectively. The introduction of the third component causes the recovered DMAc to contain the first Three-component impurities affect the quality of spandex products in the process of DMAc recycling

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