| abstract |
(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a terephthalic acid crystal and a raw dispersion medium (dispersion medium for liquid phase oxidation reaction or To find a method capable of finally obtaining high-purity terephthalic acid by substituting a dispersion medium of a raw slurry mainly composed of a dispersion medium for purification treatment after the reaction) by a gravity sedimentation method. SOLUTION: A raw slurry containing terephthalic acid crystal particles and a raw dispersion medium as main components, which are obtained by liquid phase oxidation or a purification treatment after the liquid phase oxidation, is supplied from the upper part of the dispersion medium replacement column with a replacement dispersion medium in the same column. Introduced from the lower part, stirring the lower part liquid of the same tower to a slurry state as uniform as possible, and adjusting the flow rate of the supply of the dispersion medium for replacement and the withdrawal of the replacement slurry to obtain a slurry having a higher concentration than the middle part of the same tower. While maintaining the state, both liquids are brought into contact with each other in the same column to replace the dispersion medium of the terephthalic acid crystal particles, and the obtained replacement slurry is extracted from the lower part of the column, and the liquid in the middle part of the dispersion medium replacement column is paralleled. A method for producing high-purity terephthalic acid, which is performed with or without dividing into a plurality of streams. |