RECOVERY OF TEREPHTHALIC ACID

Japanese Patent JPS62212339

A

PURPOSE: To enable the precipitation of terephthalic acid crystal having large particle diameter in the acid precipitation of an alkaline waste liquid containing dialkali metal terephthalate and to facilitate the filtration operation after acid precipitation process, by carrying out the acid precipitation in the presence of an acrylamide polymer.

CONSTITUTION: An alkaline waste liquid containing dialkali metal terephthalate and discharged from the thinning process of a polyester fiber is acidified to precipitate terephthalic acid crystal, which is filtered to recover terephthalic acid from the above waste liquid. In the above process, the acid-precipitation is carried out in the presence of 1W50ppm, preferably 2W10ppm of an acrylamide polymer in the waste liquid to obtain terephthalic acid crystal having large particle diameter and excellent filterability. The process has high recovery and excellent operation performance because of the suppressed escape of terephthalic acid crystal through a filter in the filtration after the acid precipitation. Since the water-content of the cake can be lowered, the drying treatment is simplified.

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TAN KAZUO
HIRONAKA TAKASHI
TAKAMI RYUJI

JP5668086A

September 18, 1987

March 14, 1986

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MITSUBISHI CHEM IND

C07C51/43; C07C63/26; (IPC1-7): C07C51/43; C07C63/26

Hajime Hasegawa

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