(19)

(11)

EP 0 573 446 A1

(12)

(43) Date of publication: 15.12.1993 Bulletin 1993/50 (21) Application number: 92903933.0 (22) Date of filing: 11.02.1992

(51) International Patent Classification (IPC):  B01J 20/ 12( . ) C11B 3/ 10( . ) (86) International application number: PCT/GB1992/000241 (87) International publication number: WO 1992/015396 (17.09.1992 Gazette 1992/24)

(84) Designated Contracting States: BE DE FR GB IT NL (30) Priority: 27.02.1991 GB 19910040568 (71) Applicant: Laporte Industries Limited London WC1B 3RA (GB)	(72) Inventors: TAYLOR, Roger, Skelton 26 Bembridge Close Cheshire WA8 9AA (GB) DAVIES, Mary, Elizabeth 41 St. Bridgets Close Cheshire WA2 0EW (GB) TURNER, Philip, James Cheshire WA8 7PN (GB) (74) Representative: Green, Mark Charles  Urquhart-Dykes & Lord, 91 Wimpole Street London W1M 8AH London W1M 8AH (GB)