Patent ID: 7112695

Claim:
A process for purifying a crude acrylic acid melt which contains, on a dry weight basis, ≧80% by weight of acrylic acid and, as impurities, at least ≧100 ppm by weight of acetic acid and ≧10 ppm by weight of propionic acid, which comprises: performing a suspension crystallization comprising converting a crude acrylic acid melt at low temperatures into a crude acrylic acid suspension which contains acrylic acid crystals, a residual melt and from 0.20 to 10% by weight, based on the weight of the acrylic acid contained in the crude acrylic acid melt, of water, wherein the amount by weight of impurities in the acrylic acid crystals is less than, and the amount by weight of impurities in the residual melt is greater than, the amount by weight of impurities in the crude acrylic acid melt; and passing the crude acrylic acid suspension to a wash column, whereupon the acrylic acid crystals of the remaining crude acrylic acid suspension are separated from remaining residual melt in the wash column, with the proviso that: a) the wash column is a wash column with forced transport of the acrylic acid crystals therein, and b) the acrylic acid crystals purified in the wash column are washed by a wash liquid which is a melt of purified acrylic acid crystals.