(19)

(11)

EP 0 518 971 A1

(12)

(43) Date of publication: 23.12.1992 Bulletin 1992/52 (21) Application number: 91905980.0 (22) Date of filing: 05.03.1991

(51) International Patent Classification (IPC):  H05B 6/ 02( . ) H05B 6/ 22( . ) (86) International application number: PCT/AU1991/000074 (87) International publication number: WO 1991/014353 (19.09.1991 Gazette 1991/22)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 05.03.1990 AU 19900008931 (71) Applicants: COMALCO ALUMINIUM LIMITED Melbourne, Victoria 3000 (AU) COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION Campbell, Australian Capital Territory 2601 (AU)	(72) Inventors: CONOCHIE, David, Stewart Hawthorn East, VIC 3123 (AU) NEECOWEN, Shane, Maxwell Ringwood East, VIC 3135 (AU) POULTER, Rory, Alan, Darey Altona, VIC 3018 (AU) McLEOD, Gregory Westlake, QLD 4074 (AU) (74) Representative: Hallybone, Huw George, et al  CARPMAELS AND RANSFORD 43 Bloomsbury Square London WC1A 2RA London WC1A 2RA (GB)