METHOD OF CRYSTALLIZATION

摘要

A method of multistage crystallization which comprises: sending a solution of terephthalic acid or a slurry having terephthalic acid part of which has precipitated (raw-material slurry) to a first crystallization tank; precipitating terephthalic acid in the first crystallization tank; and sending the resultant slurry containing terephthalic acid yielded (crystallization slurry) to second and succeeding crystallization tanks. It is characterized in that the crystallization slurry is sent while continuously supplying a cleaning solvent to a transfer piping connecting a preceding crystallization tank to the subsequent crystallization tank. This multistage crystallization method for treating a solution of terephthalic acid or a slurry having terephthalic acid part of which has precipitated is free from the clogging of the transfer piping even in a long-term operation as long as several months.