(19)

(11)

EP 0 020 429 A1

(12)

(43) Date of publication: 07.01.1981 Bulletin 1981/01 (21) Application number: 79901206.0 (22) Date of filing: 04.10.1979

(51) International Patent Classification (IPC):  C22B 13/ 02( . ) (86) International application number: PCT/SE1979/000199 (87) International publication number: WO 1980/000852 (01.05.1980 Gazette 1980/10)

(84) Designated Contracting States: AT CH DE FR GB LU NL (30) Priority: 12.10.1978 SE 19780010670 (71) Applicant: Boliden Aktiebolag S-114 85 Stockholm (SE)	(72) Inventor: BÄCK, Erik, Gustav S-252 60 Helsingborg (SE) (74) Representative: Lundin, Björn-Eric  Boliden Aktiebolag Box 5508 S-114 85 Stockholm S-114 85 Stockholm (SE)