GB1385799A - Method and apparatus to refine melts from solid impurities - Google Patents

Abstract

1385799 Filtration of solid impurities from melts SPETSIALNOE KONSTRUKTORSKOE BJURO GIDROIMPULSNOI TEKHNIKI SIBIRSKOGO OTDELENIA AKADEMI I NAUK SSSR and NOVOSIBIRSKY OLOVYANNV KOMBINAT 15 Feb 1972 6884/72 Heading B1D [Also in Division C7] Solid impurities are removed from a melt, such as molten tin, lead, zinc or sulphur, by immersing a rotary filter 6 in a bath 1 of the melt, the filter being rotated by drive 5 (Fig. 7) whereupon impure melt is drawn through hole 19 into the filter which retains the solid impurities but discharges refined melt through clearances between disks 16, 17 and the inner wall of cylinder 15, which may be formed with filtering units. To retain the filter below the surface of the melt, the rotor 2 is attached, by sleeve 23 and bearing 24, to a stationary pan 25 floating on the surface of the melt. Heavy impurities are prevented from precipitation in bath 1 by impeller 29 attached to the base of the filter. The solid impurities, retained in the filter, are discharged therefrom by raising disks 16 and 17 by piston 13 so that the impurities are forced through ports 26 into pan 25: When refining a metal such as tin having a large content of partially soluble impurities, e.g. arsenic, the melt temperature is gradually reduced during the filtration to about 5 to 10‹C above the crystallization point of the melt. In Fig. 8, the inlet part 19 of rotary filter 6 is immersed in the melt, and the refined melt is discharged through holes in drum 30 into a layer of molten flux. Solid impurities are removed from the filter by knife 31 which is rigidly connected to disk 16 seated on rotor 2. In refining zinc from iron, the flux may be zinc chloride. Another suitable type of filter comprises two conical dishes with their bases facing each other with very small clearance (Figs. I and 2, not shown).