This specification is essentially based on Designation BS EN 1977 : 2013 (Cu-ETP 1) and adapted to conditions unique to the Palabora Copper Rod continuous casting process.
The casting process is using the Southwire Continuous Rod (SCR) technology to produce electrolytic tough pitch (ETP) copper rod in 8 mm diameter rod size. Electrolytic Tough Pitch (ETP) copper is electrolytically refined copper which contains mostly oxygen as an impurity.
The SCR process is a combination of continuous melting, casting, rolling, pickling and coiling operations. Copper cathode is continuously melted in a vertical shaft furnace and continuously transferred to a cylindrical holding furnace which stabilizes the flow and provides uniform chemistry and temperature. Molten copper from the holding furnace is continuously transferred by means of covered heated launders to the tundish, which is located directly above the casting machine. The tundish is equipped with an automatic metal pouring system for the flow control of molten copper into the casting machine.
The SCR system uses Liquefied Petroleum Gas (LPG) as the combustion gas to melt the copper in the shaft furnace, keeping the holding furnace and launder system at optimal temperature.
The SCR caster system consists of a wheel having at its periphery a groove which is closed by means of an endless steel belt which, in effect, becomes the fourth side of the mold. The mold is cooled by means of water sprays and the molten copper solidifies in less than 30 seconds. The bar comes out of the caster at a very high speed of 20 to 28 cm/s and is guided to an in-line, no twist rolling mill through a bar preparation unit. This unit removes the belt side corners and any loose scale or oxide adhering to the surface.
The bar then enters the rolling mill where it is reduced to the final rod size by means of a series of vertical and horizontal roll stands. The rod exits the last stand at approximately 612 °C and enters an in-line alcohol based pickling system. The resulting rod has a bright copper colour and is free of surface oxides. Finally the rod is coated with wax to retard surface oxidation and coiled continuously into packages weighing on average 4.6 tonnes.