Patent ID: 8167974

Claim:
A terephthalic acid purge process comprising: (a) subjecting an oxidizer purge stream formed in a terephthalic acid process to evaporation in a 1 st evaporator zone to produce a 1 st 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 water; (b) adding water to said concentrated purge stream in a 1 st 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 2 nd vapor stream and a super concentrated purge slurry stream; and (d) adding water to the super concentrated purge slurry stream in a 2 nd mix zone to produce a water rich super concentrated purge slurry, and (e) filtering said water rich super concentrated purge slurry in a solid-liquid separation zone to form a filter cake and mother liquor; (f) washing said filter cake with a wash feed in said solid-liquid separation zone to form a washed filter cake, and wash liquor; and (g) adding water to said mother liquor in a 3 rd mix zone and subjecting an aqueous mixture so formed to extraction with an extraction solvent to produce an extract stream and a raffinate stream comprising the metal catalyst.