| abstract |
A process for the production of purified terephthalic acid (PTA) from crude terephthalic acid (CTA) comprising mixing the CTA with an aqueous medium to form an aqueous CTA mixture, heating the mixture to dissolve substantially all of the CTA in the aqueous medium by introducing into the aqueous mixture vapour having a temperature greater than that of said mixture and then chemically reducing impurities in the aqueous solution of CTA followed by recovery of PTA by a crystallisation process. The vapour is typically steam derived from the crystallisation process and may be introduced into the aqueous CTA mixture by means of an injection device (30) (Figures 2 and 3). |