4. Cost of metallurgical operations

The production capacity of mines and pyrometallurgical plants grew steadily from 1985 to 2000, from 5.8 Mt/year in 1985 to 13 Mt/year in 2000, as production, driven by growing demand, increased steadily from 1960 to 2000. At the same time, manufacturing costs continued to fall, for the following reasons:

• oxygen smelting, which results in increased production, low energy consumption, lower gas volumes and higher SO ₂ concentrations in the gases, making it possible to manufacture inexpensive sulfuric acid;

• lower costs, since continuous melting and conversion both reduce personnel costs and enable surplus energy to be resold or reused on site;

• recovery of copper and other metals from the slag by continuous smelting in an electric...