Purification recovering method for sodium thiocyanate solution of acrylic fiber production

Abstract

A method for purifying and recovering sodium thiocyanate aqueous solution in acrylic production relates to a sewage treatment method, in particular to a method for purifying and recovering sodium thiocyanate aqueous solution in the acrylic production process. Including buffer storage, filtration, primary nanofiltration, secondary nanofiltration, evaporation and concentration process. After the purification and recovery of the present invention, the quality of sodium thiocyanate in the waste liquid accounts for no more than 5% of the total mass of sodium thiocyanate in the raw feed solution, and the recovery of sodium thiocyanate can reach more than 98%, and the production process does not need to add Chemical raw materials such as caustic soda, sulfuric acid, diatomaceous earth, etc., compared with the usual traditional purification and recovery methods, one evaporation and concentration process is reduced, the amount of desalted water is reduced by more than 80%, the amount of evaporation and concentration water is also greatly reduced, and the amount of sewage discharge is also greatly reduced.

Description

technical field [0001] The invention relates to a sewage treatment method, in particular to a method for purifying and recovering sodium thiocyanate aqueous solution in the acrylic production process. Background technique [0002] Most of the acrylic production process uses sodium thiocyanate solution as the polymerization solvent and silk-melting cooling solvent. In the production process, impurities such as sulfate ions, iron ions, β-SPN, β-SPA, etc. will enter the thiocyanate in sodium solution. Sodium thiocyanate solution is recycled in the acrylic production process, and the accumulation of impurities will cause many adverse effects. Therefore, there is a special solution purification and recycling production process to remove impurities. [0003] There are multiple methods for purifying sodium thiocyanate solution at present. Preliminary purification usually adopts sodium hydroxide precipitation method combined with diatomaceous earth filtration or ion exchange method...

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Problems solved by technology

[0004] The recovery rate of traditional sodium thiocyanate solution purification recovery method can only reach 90% usually, because the high energy consumption of evaporation concentration crystallization and chemical agent (diatomaceous earth, The consumption of sulfuric acid, sodium hydroxide) not only consumes high energy and material costs, but also produces a large amount of waste water and waste solids, and the quality of sodium thiocyanate solution will also be affected due to the occurrence of side reactions and impurities brought in with chemical agents

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