FIELD: production of polymer fiber. SUBSTANCE: suspension of terephthalic acid in acetic acid is produced by oxidation of n-xylene in acetic acid: removal of water by evaporation of water and acetic acid with return of acetic acid to the stage of oxidation. Terephthalic acid is separated from reaction medium in the first zone and precipitate remains on belt. This precipitate is washed with the first aqueous medium in the second zone, and removed from belt in the third zone and mixed with the second aqueous medium. Reaction medium is withdrawn from the first reaction zone to the stage of oxidation, and terephthalic acid is withdrawn. In this case, the process is carried out at higher pressure on the side of movable belt to which suspension is supplied as compared with that of its opposite side. Pressure differential is 0.1-15 bars is preferable version after additional purification with use of water obtained at the previous stage. EFFECT: higher efficiency. 31 cl, 2 dwg, 1 tbl
