GB544112A - Improvements in the method of melting copper - Google Patents

Abstract

544,112. Melting copper. FAIRWEATHER, H. G. C. (International Smelting & Refining Co.). Dec. 2, 1940, No. 17150. [Class 51 (ii)] A method of melting cathode copper consists in heating the melting chamber of a fuel-fired muffle furnace to a temperature above the melting point of copper, maintaining a bath of substantially oxygen free molten copper in the melting chamber with its surface free from slag or other medium impeding the transfer of radiant heat thereto, maintaining in the melting chamber a reducing atmosphere, introducing the cathode copper into the melting chamber so as to prevent the admission of air, melting the copper so introduced while maintaining the slag free bath of oxygen free molten copper and withdrawing oxygen free molten copper from the melting chamber. The melting chamber 16, Fig. 3, is externally heated by burners 19 from which heat is radiated through the arch 18 formed of silicon carbide. The cathode copper sheets 23, Fig. 2, are fed from each side of the melting chamber down inclined floors 24 through an air seal consisting of a tube 25 open at the bottom and containing washers 27 supported freely on a rod 28 and contacting the cathode copper sheets 23. An atmosphere of carbon monoxide and nitrogen is introduced to the melting chamber through pipes arranged in the wall on either side of the discharge well 31 communicating with the tap hole 29. Molten copper is discharged through a launder 32 leading to a tilting casting ladle 33. The launder is heated by a flue 34 leading from a combustion chamber heated by a burner. Reducing gas is supplied by pipes 491, 49 and 50 to the upper and lower ends of the launder and to a hood 45 covering the mould 44. Phosphorus or silicon may be added to the molten copper through a funnel 42. The reducing gas used in the melting chamber 16, discharging launder 32 and hood 45 is obtained by treating the exhaust combustion gases from the furnace. Such treatment consists in passing the gases from the flue 20 by means of a pump 53, Fig. 6, through a water chamber 52, .water spray tower 54, iron oxide tower 55, moisture trap 56 and electro dryers 57 filled with activated alumina. The purified dried gas consisting principally of carbon dioxide and nitrogen is then passed over electrically heated charcoal in reducers 58 and thence through filters 59 to the supply main 48. The covering tiles of the launder may be removed and the molten metal flowing through the launder may be covered with charcoal more or less so that the molten copper is exposed sufficiently to the air to incorporate therewith the desired amount of oxygen to produce a flat set upon casting and cooling.