GB1029132A - Improvements in the production of crystals from solutions - Google Patents

Abstract

Crystal growth is effected by contacting a supersaturated solution derived from a feed liquor and recycled mother liquor with a suspension of growing crystals in an aqueous solution. The supersaturated solution has a supersaturation of less than 0.5 gm. of solute per 100 gm. of solvent. The difference in concentration of the feed and mother liquors is maintained below a predetermined value (12 gm./100 gm. water for adipic acid and 2.5 gm./100 gm. water for benzoic acid). A portion of the mother liquor may be fed to a similar subsequent crystallization stage. The supersaturated solution may be obtained by passing a mixture of feed and a portion of the mother liquor to an evaporator (Fig. 2, not shown) or may be formed in the crystallizer itself from supersaturated feed and mother liquor (Fig. 4, not shown).ALSO:Crystal growth is effected by contacting a supersaturated solution derived from a feed liquor and recycled mother liquor with a suspension of growing crystals in an aqueous solution. The supersaturated solution has a supersaturation of less than 0.5 gm of solute per 100 gm of solvent. The difference in concentration of the feed and mother liquors is maintained below a predetermined value (12 gm/100 gm water for adipic acid and 2.5 gm/100 gm water for benzoic acid). A portion of the mother liquor may be fed to a similar subsequent crystallization stage. The supersaturated solution may be obtained by passing a mixture of feed and a portion of the mother liquor to an evaporator (Fig. 2, not shown) or may be formed in the crystallizer itself from supersaturated feed and mother liquor (Fig. 4, not shown).