Recycling method for mother liquor of N-(phosphonomethyl)iminodiacetic acid

Abstract

The invention relates to a recycling method for mother liquor of N-(phosphonomethyl)iminodiacetic acid. According to the invention, with iminodiacetonitrile as a main raw material, through an alkaline hydrolysis process or an acidolysis and alkaline hydrolysis combined process, ammonia gas is recycled or / and monosodium diacid salt is generated by addition of ammonium salt and double decomposition reaction of deamination under heating; a qualified sodium chloride by-product is precipitated and separated through direct hydrolysis of the mother liquor of N-(phosphonomethyl)iminodiacetic acid and common-ion effect of hydrogen chloride; acidic mother liquor can be recycled; the mother liquor, the mother liquor incapable of being reused and washing water can be completely precipitated and separated through the addition of calcium hydroxide; the obtained precipitate can regenerate raw materials and products through an aqueous solution of acid or alkali; N-(phosphonomethyl)iminodiacetic acid is reused or separately synthesized; and the regenerated calcium hydroxide can be repeatedly reused. The novel recycling method provided by the invention can realize clean production of N-(phosphonomethyl)iminodiacetic acid and cyclic utilization of by-products with high added value.

Description

technical field [0001] The invention relates to a clean production process of a glyphosate intermediate diglyphosate, in particular to a method for recycling a diglyphosate mother liquor, and belongs to the technical field of pesticides and fine chemicals. Background technique [0002] Diglyphosate is an intermediate for the preparation of glyphosate, a broad-spectrum herbicide with the largest global consumption. The chemical name of glyphosate is N-phosphonomethylglycine. The control of deep-rooted malignant weeds is very effective. In recent years, the sales volume has gradually increased. It ranks first among the 50 largest pesticide varieties in the world. The market size exceeds 10 billion US dollars. It has been registered and widely used in more than 130 countries around the world. [0003] The industrial production of bisglyphosate is obtained by using iminodiacetic acid, phosphorous acid and formaldehyde under the catalysis of hydrochloric acid, heating to reflux c...

AI Technical Summary

Problems solved by technology

This method has too many times of solid-liquid separation, and the yield of diacid is only about 80%. A large amount of diacid waste water containing salt is concentrated and desalted, and the method of regeneration of evaporative condensate is used. The energy consumption is high, and the quality of salt is poor, so it is difficult to use.

[0007] At present, most enterprises adopt the method of desalting concentrated diglyphosate wastewater and regenerating evaporative condensate, but the existence of formaldehyde leads to biochemical difficulties, and there are problems such as high energy consumption, poor quality of waste salt, and difficulty in utilization.

There is no good method for the treatment of wastewater and mother liquor produced in the dinitrile process. Although there are membrane technologies for wastewater treatment and desalination processes, there are large initial investment, frequent clogging and damage of membranes, short service life, and high operating costs. The high problem has not yet been well resolved

This process saves the consumption of alkali and hydrochloric acid, but increases the consumption of ammonia and the refining of crude products. The process is longer and the investment is relatively large.

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