Patent ID: 8466312

Claim:
A process comprising: (a) subjecting an oxidizer purge stream formed in a terephthalic acid synthesis process to evaporation in a 1st evaporator zone to produce a vapor stream and a concentrated purge stream; wherein said oxidizer purge stream comprises a carboxylic acid, a metal catalyst, impurities, water and a solvent; wherein said solvent comprises acetic acid and (b) adding water to said concentrated purge stream in a mixing zone to produce a water rich concentrated purge stream; (c) subjecting said water rich concentrated purge stream to evaporation in a 2 nd evaporator zone to produce a solvent rich stream and an intermediate concentrated purge slurry steam; (d) subjecting said intermediate concentrated purge slurry to evaporation in a third evaporator zone to produce a super concentrated purge slurry, wherein said 3 rd evaporator zone comprises an evaporator operated at a temperature of about 20° C. to about 70° C.; wherein said water being added in the mixing zone is added in an amount sufficient to result in said super concentrated purge slurry having a water content of about 5.0 wt % to about 25.0 wt % (e) filtering said super concentrated purge slurry in a solid-liquid separation zone to form a filter cake and mother liquor; and (f) washing said filter cake with a wash feed in said solid-liquid separation zone to form a washed filter cake, and wash filtrate.