ALUMINUM PURIFICATION METHOD Russian patent published in 1998 - IPC

FIELD: aluminum production. SUBSTANCE: in an aluminum purification method involving vacuum aging and zone melting, the former operation is conducted at 680-1000 C for 6 to 54 h using controlled stepped heating and cooling with 3 to 9 heater sections in automated mode with heating rate 0.1-5.0 C/min and cooling rate 0.08-0.8 C/min. Zone recrystallization is conducted in the following manner: first three zone passages with crystallization front displacement velocity 1.8-2.5 mm/min and zone width from 1/8 to 1/10 ingot length and subsequent passages with velocity 0.4-1.0 mm/min and zone width from 1/15 to 1/20 ingot length, total number of passages not exceeding 10. As a consequence, final distribution of metal admixtures with simultaneous removal of volatile admixtures is attained resulting in that initial part of ingot is enriched in admixtures with distribution coefficient higher than 1 (Cr, Ti, Mo, W, Hf, etc.) and final part of ingots enriched in admixtures having distribution coefficient below 1 (Fe, Cu, Si, Ni, etc.). EFFECT: enhanced metal purification efficiency. 1 tbl