A mother liquor treatment process and system for separation and concentration of dichloropyralic acid materials

Abstract

The invention discloses a mother liquor treatment process and system applied to clopyralid material separation and concentration. The mother liquor treatment system comprises a primary sedimentation tank, a raw water tank, a reaction kettle, a sedimentation tank, a sand filter tank, an ultrafiltration system and a Super RO (reverse osmosis) membrane module which are connected sequentially as well as an evaporator connected with the Super RO membrane module, wherein raw clopyralid mother liquor enters the primary sedimentation tank, both the raw water tank and the reaction kettle are provided with chemical feeders, and the raw water tank and the reaction kettle are communicated through a lift pump; a sludge valve is arranged at the bottom of the sedimentation tank, the sand filter tank is provided with a backwash pipe, a backwash water outlet end of the backwash pipe is communicated with the reaction kettle, and the ultrafiltration system is communicated with the reaction kettle. According to the mother liquor treatment system, design is improved according to the characteristics of the clopyralid material, softening is performed firstly for hardness removal, then ultrafiltration and special RO membrane filtration are performed, and small amount of concentrated water is subjected to evaporative crystallization finally; the evaporation cost is reduced, the influence of a thermal oxidation action on the material is avoided in the whole process, the mother liquor recovery quality is guaranteed, the energy consumption can be reduced obviously, and accordingly, the operation cost is reduced greatly.

Description

Technical field [0001] The present invention relates to the field of mother liquor treatment for the preparation of herbicidal pesticides. Specifically, it relates to a mother liquor treatment process and system for the separation and concentration of clopyralid materials. Background technique [0002] Dichloropicolinic acid (3,6-DCP) (Bike grass) is a new type of nitrogen-containing herbicide, which was researched and developed in the 1990s. It has a unique structure, low toxicity, high activity, good selectivity, and is environmentally friendly. , is one of the heterocyclic (pyridine) pesticide varieties among the top ten new green pesticides currently being developed internationally. [0003] At present, there are two main processes for producing clopyralic acid in China: one is the chemical dechlorination method, which uses excess hydrazine hydrate to reduce tetrachloropicolinic acid in an alkaline aqueous solution to generate clopyralic acid. This process has low produc...

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Problems solved by technology

Due to the limitations of the diaphragm and roll structure design, the traditional roll-type reverse osmosis membrane has high requirements on the quality of the influent water and is not suitable for sewage treatment. It has poor pollution resistance, low sewage recovery rate, high cleaning frequency, and short service life. Even if ultrafiltration and electrodialysis are used for pretreatment, the feed liquid concentration in the feed water of the reverse osmosis membrane is still high. Long-term operation will lead to fouling of the reverse osmosis membrane, decrease in membrane flux, and lower recovery rate.

In addition, although the operating cost of this process is 75 yuan / ton (membrane replacement time is calculated as 2 years), which is 150 yuan / ton compared with the total evaporation process, the relative cost is lower, but for enterprises, high input and low output are still not the most efficient way

However, the installation of electrodialysis equipment is more complicated, the desalination effect is not complete, generally 75%, the water recovery rate is low, generally 50%, the power consumption and water consumption are high, and the turbidity requirements for influent water are also very strict. , the cathode and the membrane are easy to scale during operation, which affects the quality of the effluent water and shortens the use of the instrument

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