METHOD FOR INDUSTRIALLY RECOVERING TEREPHTHALIC ACID FROM CRUSHED PRODUCT OF RECOVERED POLYETHYLENE TEREPHTHALATE

摘要

PROBLEM TO BE SOLVED: To provide a process for practically and industrially recovering terephthalic acid in a high recovery rate. SOLUTION: This method for industrially recovering terephthalic acid from the crushed product of recovered polyethylene terephthalate comprises (1) a reaction decomposition process for continuously reacting and decomposing the crushed product of the recovered polyethylene terephthalate into a terephthalate and ethylene glycol in the presence of an alkali in an amount of the same or larger moles as or than that of the polyethylene terephthalate in ethylene glycol, (2) a solid-liquid separation/ dissolution/impurity removal process for separating the ethylene glycol from the reaction decomposition slurry of the terephthalate and the ethylene glycol, dissolving the solid terephthalate in water, and removing insoluble impurities, (3) a neutralization/ precipitation process for neutralizing the aqueous solution of the terephthalate with an acid to precipitate the terephthalic acid, (4) a solid-liquid separation/washing process for subjecting the terephthalate crystal precipitation slurry to a solid-liquid separation to separate the terephthalic acid crystals, and (5) a drying/crushing process for drying and crushing the washed terephthalic acid.