Purification of frozen crystal layers

US4795571A · kind A · utility

Assignee

• BASF SE

Inventors

• Bernhard Holzknecht · Ellerstadt, DE
• Hugo Fuchs · Ludwigshafen, DE
• Eckhard Hetzel · Frankenthal (Pfalz), DE
• Klaus Wintermantel · Weinheim, DE
• Peter Thoma · Mannheim, DE

Key dates

• Filing date: Feb 10, 1988
• Grant date: Jan 3, 1989
• Expiry date: Feb 10, 2008

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01D9/005
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Frozen crystal layers are purified by a process in which these crystal layers, after they have been frozen out from a melt or solution on a cooling surface, are brought into contact with a purifying liquid and thus purified over their entire thickness, after which the said layers are separated from the purifying liquid and then melted, wherein the temperature of the crystal layers and of the purifying liquid is close to the melting point or solubility temperature, mass transfer at the phase boundary is intensified by forced convection, and this purification is carried out in the course of from 1 to 60 minutes on layers having a thickness of from 0.2 to 10 mm.