Method for recovering acetic acid, cobalt and manganese from discharged residues of PTA (purified terephthalic acid) film evaporator

Abstract

The invention relates to a method for recovering acetic acid, cobalt and manganese from discharged residues of a PTA (purified terephthalic acid) film evaporator. The method comprises steps as follows: the discharged residues of the film evaporator are beaten with a small amount of water and resin effluent to obtain slurry, the slurry is subjected to solid-liquid separation, filtrate is subjected to sodium type cation exchange resin removal, the most of resin effluent is cooled and returned for beating the discharged residues of the film evaporator, and acetic acid is recovered from a small part of resin effluent with an extraction method or an evaporation method; saturated resin is desorbed by a desorbent, a precipitant is added to a desorbed solution so as to form cobalt and manganese precipitation, the cobalt and manganese precipitation is filtered, and a filter cake is sufficiently washed by water to obtain a cobalt and manganese mixture. The method has the advantages as follows: firstly, the concentration of acetic acid in a residual liquid is increased by reducing residual liquid extraction and increasing circulation, so that the economy of the acetic acid recovering method is improved; secondly, the acetic acid is recovered with the extraction method, thus, the energy is saved, and the recovery rate is increased; thirdly, more than 90% of the desorbent can be recycled, all that is required is to supplement a small quantity of desorbent lost during operation, and accordingly, the economy is greatly improved.

Description

technical field [0001] The invention relates to a method for recovering acetic acid and cobalt-manganese from a PTA film evaporator blanking residue. The film evaporator blanking residue comes from a thin film evaporator of an oxidation mother liquor impurity removal unit in the production process of terephthalic acid. Background technique [0002] Purified Terephthalic Acid (PTA) is the main raw material for the production of polyester fibers and resins. Currently, it is mainly produced by air oxidation of p-Xylene (PX). In the PTA production process, in order to control the product quality, it is necessary to extract part of the oxidized mother liquor to remove the impurities in the unit to remove the impurities in this part of the mother liquor. The form of material residue is discharged out of the system, thus forming the PTA thin film evaporator discharge residue. PTA thin film evaporator blanking residue accounts for 0.5-0.9wt% of PTA output. If the national PTA prod...

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Problems solved by technology

Chinese patents ZL200810229404.2, ZL97103884.8, and ZL97119183.2 mention that acetic acid is recovered by evaporation and condensation, and the recovered acetic acid-water solution is returned to the PTA device, but this is only applicable to the case of high acetic acid concentration

In these methods, the resolving agent cannot be recycled, and the resolving agent consumes a lot

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