GB278774A - Improvements in rotary chemical furnaces - Google Patents

Abstract

278,774. Tocco, L., and Landi, M. June 8, 1926. Resistance furnaces. - A continuously-operating rotary furnace heated by internal resistance elements is divided by partitions into a number of reaction chambers, and means are provided by which materials, can be automatically introduced and withdrawn, and gases &c. resulting from the reactions can be removed. In the plant shown, which is more particularly adapted for the treatment of ores containing lead and zinc, the material passes in series through three rotary drums I, O, Q, of which the first is divided by partitions 27 into three zones Ir, Iz, Iy, while the second and third are separated by a fixed water-cooled head 80. In the first zone Ir the ore is dried at a temperature of about 150‹ C., in the second Iz the lead sulphide is converted to oxide at a temperature of 380‹ C. by air supplied through the pipe 42, and in the third the oxide is reduced by carbon supplied by a screw conveyer 35 and delivered between the second and third zones through a passage in the partition. The third zone is heated to a temperature of about 500‹ C. by resistances 43, which are embedded in zirconia in grooves in the furnace shell and are supplied with current by slip-rings and brushes. The molten lead is withdrawn through a pipe 60, and the remainder of the charge passes through a water-cooled magnetic separator 64 to the chamber 10, where the zinc sulphide is converted to oxide at a temperature of about 600‹ C. In this zone the surplus heat is utilized to generate steam in a stationary boiler O<1>. The oxide then passes through a rotary chamber 84, in which it is mixed with carbon supplied through a pipe 86, and into the chamber where a temperature of 1400‹ C. is maintained by electric resistances. Here the zinc is reduced, and the vapourized metal is reoxidized by air supplied through a passage 92 in the fixed head 80. The oxide is withdrawn through the conduit 103, while the solid residue is discharged through the passage 100 on to the conveyer 101. The ore is supplied to the zone Ir through the shoot 12 and the charging apparatus comprises a hopper 1, crusher 2, and rotary valves 4, 10 driven through gearing from the furnace. Gases are withdrawn from the zones Ir, Iy and O through pipes 22, 56 and 76 respectively.