(19)

(11)

EP 0 305 512 A1

(12)

(43) Date of publication: 08.03.1989 Bulletin 1989/10 (21) Application number: 88904020.0 (22) Date of filing: 18.03.1988

(51) International Patent Classification (IPC):  B01D 53/ 50( . ) C01C 1/ 16( . ) (86) International application number: PCT/US1988/000897 (87) International publication number: WO 1988/007022 (22.09.1988 Gazette 1988/21)

(84) Designated Contracting States: AT BE CH DE FR GB IT LI LU NL SE (30) Priority: 18.03.1987 US 19870027566 (71) Applicant: RADIAN CORPORATION Austin, TX 78720-1088 (US)	(72) Inventors: BURKE, John, Michael Austin, TX 78731 (US) COLLEY, James, David Austin, TX 78731 (US) (74) Representative: Wood, Anthony Charles, et al  Urquhart-Dykes & Lord 91 Wimpole Street London W1M 8AH London W1M 8AH (GB)