GB678261A - Method of removing zinc from copper base alloys containing zinc - Google Patents

Abstract

678,261. Distilling zinc. EVANS, A. J. S., (Revere Copper & Brass, Inc.). Jan. 26, 1945, No. 2129/45. [A Specification was laid open to inspection under Sect. 91 of the Acts, July 28, 1945.1 Class 82(i) [Also in Groups XI and XII] A method of removing zinc from copper base alloys containing zinc comprises heating a body of the molten alloy having a free surface to at least the melting point of its non-zinciferous content to evaporate zinc therefrom under substantially non- oxidizing conditions in the presence of elemental carbon having an incandescent surface intersecting the said free surface of the molten alloy, the residual amount of zinc in the molten metal from which it is so removed being not greater than 10 per cent. The alloy may be made to flow substantially continuously through a container which provides a relatively large free surface in proportion to the volume of the alloy contained therein. In the apparatus shown in Fig. 2 alloy is fed to the melting furnace through a screw conveyer 93, gate 99 and duct 101 which collectively serve to prevent ingress of air to the furnace. The alloy is melted by heat radiated from resistance heaters 73. Any dross. formed is removed by duct 81 and molten alloy is taken from the bottom of the furnace via ducts 81 and 59 to the evaporation furnace. Molten alloy collects in a shallow tray at least the side walls of which comprise elemental carbon. The alloy and the carbon surface are heated by radiation from the resistance heater 35 and from the refractory roof 45, the zinc vapour evolved being removed by duct 69 to a condenser. Residual metal discharges into a pot 63 from which it is tapped as required from duct 65. Alternatively continuous passage of metal through the furnace may be obtained by withdrawing molten metal through an air lock at the outlet. Inert gas may be introduced into the furnace through pipe 125 to dilute the zinc vapours and sweep them towards the vapour outlet 69. Dilute zinc vapour enters a zinc condenser, Fig. 18, at lower header 175 and rises through tubes 177 which are maintained at the required condensation temperature by flames from gas jets 185 outside each tube. By suitable adjustment of the condenser temperature zinc is condensed in liquid form and runs downward through the tubes into the lower header from which it is removed by duct 193. Uncondensed gases are removed through a vent 179 in which a valve 181 serves to adjust the gas pressure in the furnace and condenser.