GB860149A - Improved gas collecting means for electrolytic aluminium furnaces - Google Patents

Abstract

860,149. Etectrolytic furnaces. ELEKTROKEMISK. A.S. Oct. 24, 1957 [Oct. 24 1956], No. 33262/57. Class 39 (3). An electrolytic aluminium furnace of the type having an anode 3 extending through a permanent sheath-like casing 6 and supplied with current through vertical contact rods 4 inserted into the anode and serving to support it has a gas-collecting ring 11 or 13 connected to a source of suction and secured to the casing 6 in a position surrounding the anode and spaced above the bath crust 8 so that it collects furnace gas diluted with excess air from the furnace room. In Fig. 1 the ring is a secondary ring 11 placed directly above a primary gascollecting ring 10 surrounding the anode at the surface of the bath to collect furnace gas in concentrated unburnt form; and the secondary ring 11 has a vertical or inclined outer wall furnished with adjustable ports 12 through which a variable amount of excess air with escaped furnace gas is drawn into the ring by a fan either constantly or when the crust 8 is broken and the furnace is being recharged at 9. In Fig. 2 the secondary gas-collecting ring comprises an open-bottomed fume hood 13 placed at or adjacent the upper edge of the anode casing 6 and provided with a suction pipe 14. Concentrated gas collected in the primary ring 10 is burnt in a burner to which the gaseous mixture collected by the hood 13 is fed as a source of oxygen for combustion. In the modification shown on the left of Fig. 2, the primary ring 10 is omitted, and concentrated gas collecting between the melt and the crust is led by pipes or holes in the crust near the anode to the hood 13. Tar fumes from this space may be burnt in a burner 15 supported at 16 on the lower part of the iron, casing 6. The secondary rings 11 and 13 may be constructed as platforms for furnace operators.