Method for treating N-Phosphonomethyl iminodiacetic acid (PMIDA) mother liquid

Abstract

The invention relates to a method for treating an N-Phosphonomethyl iminodiacetic acid (PMIDA) mother liquid which is obtained by producing glyphosate by an iminodiacetic acid method. The method includes adding alkaline substances into the PMIDA mother liquid, adjusting potential of hydrogen (pH) of the mother liquid to be in a range from 9 to 12, subjecting the mother liquid to multiple-effect evaporation and concentration, filtering to obtain a filter cake and a filter liquid, washing the filter cake to remove organic matters to obtain inorganic salt, and burning the filter liquid to obtain pyrophosphate. The method for treating the PMIDA mother liquid has the advantages that chlorine containing substances and phosphorus containing substances in the mother liquid can be recycled in a high yield coefficient mode, the process is simple, the environment-friendly benefit is remarkable, and the method is suitable for popularization and usage in industrial mass production.

Description

technical field [0001] The invention relates to a treatment method of diglyphosate mother liquor, in particular to a treatment method of diglyphosate mother liquor obtained by producing glyphosate by iminodiacetic acid method. technical background [0002] As a high-efficiency, broad-spectrum, and low-toxic herbicide, glyphosate has become more and more widely used and has become the most widely used herbicide in the world. At present, there are many methods for preparing glyphosate in China. The dialkyl phosphate method and the iminodiacetic acid method, when using the iminodiacetic acid route to prepare glyphosate, an acidic mother liquor containing chloride ions, sodium ions, diglyphosate and other components will be produced. In the current production process , it is more difficult to deal with this kind of mother liquor, and it is usually treated as waste water, which not only wastes resources, but also pollutes the environment. [0003] In the patent application of Ch...

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Problems solved by technology

[0002] As a high-efficiency, broad-spectrum, and low-toxic herbicide, glyphosate has become more and more widely used and has become the most widely used herbicide in the world. At present, there are many methods for preparing glyphosate in China. The dialkyl phosphate method and the iminodiacetic acid method, when using the iminodiacetic acid route to prepare glyphosate, an acidic mother liquor containing chloride ions, sodium ions, diglyphosate and other components will be produced. In the current production process , it is difficult to deal with this kind of mother liquor, and it is usually treated as waste water, which not only wastes resources, but also pollutes the environment

[0003] In the patent application of Chinese patent CN1422275A and CN1837105A, only the sodium chloride in the waste water is recycled, and the bisglyphosate is not utilized; in the patent application of the Chinese patent CN101041527A, the bisglyphosate in the waste water is recycled, but the process is complex, time-consuming and laborious Chinese patent CN101348266A adopts nanofiltration membrane to concentrate the mother liquor, reclaims the bisglyphosate in the concentrated solution, the light liquid is through evaporation and crystallization, roasting, and phosphorus removal process obtains refined sodium chloride, although reclaimed bisglyphosate and by-product sodium chloride, But, the rate of recovery is not very high, and from the data of its embodiment 1, the recovery of bis-glyphosate is only 91.2%, and the rate of recovery of sodium chloride cannot reach 90%.