A kind of methionine crystallization mother liquor processing method

Abstract

The invention relates to a method for treating methionine crystallization mother liquor, which uses methionine crystallization mother liquor extracted in the production process of methionine potassium salt as a raw material, and comprises the following steps: (1) heating and concentrating the extracted methionine crystallization mother liquor to obtain methionine potassium and carbonic acid Potassium mixed solution is passed into carbon dioxide gas then, obtains respectively the potassium bicarbonate solid and the potassium bicarbonate filtrate containing methionine, and the solid returns to 5-(2-methylthioethyl)-hydantoin hydrolysis; (2 ) The potassium bicarbonate filtrate obtained in step (1) is subjected to bipolar membrane electrodialysis treatment, the acid chamber obtains an aqueous solution containing organic matter, which is concentrated and incinerated, and the alkali chamber obtains a dilute potassium hydroxide aqueous solution, which is returned to 5‑(2‑ Methylthioethyl)‑hydantoin hydrolysis. The method again uses carbon dioxide acidification and bipolar membrane electrodialysis to fully recover methionine and potassium ions in the mother liquor, avoids the loss of valuable compounds in the mother liquor, and reduces production costs.

Description

technical field [0001] The invention belongs to the field of chemical industry, and in particular relates to a method for treating methionine crystallization mother liquor extracted in the production process of methionine potassium salt. Background technique [0002] The known mainstream production method of methionine is to hydrolyze 5-(2-methylthioethyl)-hydantoin aqueous solution in the presence of potassium carbonate to obtain an aqueous solution of potassium methioninate containing potassium carbonate, and then to contain potassium carbonate The potassium methionine potassium methionine aqueous solution is passed through carbon dioxide to neutralize, and then the methionine is crystallized and separated, and the wet product of methionine and the potassium bicarbonate aqueous solution (filtrate) containing methionine are respectively obtained; the potassium bicarbonate aqueous solution (filtrate) containing methionine is concentrated and returned to 5-(2-Methylthioethyl)...

AI Technical Summary

Problems solved by technology

[0004] Add water-miscible organic solvents such as methanol, acetone and isopropanol in the mother liquor, although a large amount of methionine and potassium bicarbonate can be precipitated, but after taking methionine and potassium bicarbonate, the mother liquor not only contains methanol or acetone, Isopropanol, but also contains other impurities such as methionine dimer, potassium formate, potassium propionate, potassium acetate, potassium butyrate, potassium carbonate, polyvinyl alcohol, sorbitan laurate, hydroxypropyl methylcellulose Etc., in the synthesis of cyanohydrin between methionine and hydrocyanic acid, citric acid buffer or acetic acid buffer is added as a cyanation catalyst, and these catalysts will eventually be brought into the methionine crystallization mother liquor, and will be recycled with the methionine crystallization mother liquor It is impossible for these impurities to be precipitated by adding an organic solvent and remain in the mother liquor

Such mother liquor treatment is relatively difficult, because a large amount of organic solvent is used at first, so the solvent needs to be recovered now, and the organic solvent is recovered through distillation and rectification, and the raffinate after recovery of the organic solvent must be incinerated before it can be recovered. so that these impurities do not return to the methionine production system

Solvent recovery consumes a lot of energy and requires a lot of equipment investment, and the loss of solvent is inevitable, which increases the production cost of methionine