Process for producing highly pure terephthalic acid

摘要

There are disclosed a method for replacing a dispersion medium wherein an original slurry comprising solid particles and an original dispersion medium is introduced in a dispersion medium replacement column at the top thereof, a replacing dispersion medium is introduced in the column at the bottom thereof to replace the original dispersion medium with the replacing dispersion medium, the resultant replaced slurry comprising the solid particles and the replacing dispersion medium is taken out from the column at the bottom thereof, and the original dispersion medium is taken out from the column at the top thereof, which method comprises dividing the fluid in the intermediate portion into a plurality of parallel streams, stirring the slurry in the bottom of the column to uniformize the slurry, and controlling the feed rates of the replacing dispersion medium and the replaced slurry to maintain the slurry in the bottom portion of the column at a concentration higher than that of the slurry in the intermediate portion of the column; an apparatus for carrying out the method; and a process for producing highly pure terephthalic acid from the slurry comprising an original dispersion medium and crystalline particles of terephthalic acid. The method and apparatus are capable of producing highly pure terephthalic acid at a high replacement efficiency of the dispersion medium with simplified equipment in an extremely advantageous manner.