| Popis: |
Virtually all the molten copper produced by smelting/converting is subsequently electrorefined. It must, therefore, be suitable for casting into thin, strong, smooth anodes for interleaving with cathodes in electrorefining cells. This requires that the copper be fire refined to remove most of its sulfur and oxygen that causes blisters and bubbles. This chapter describes the process of fire refining for removing blisters. It is prevented by removing sulfur and oxygen from molten copper by air oxidation, then hydrocarbon reduction. The air and hydrocarbons are usually injected into the molten copper via one or two submerged tuyeres in a rotary anode furnace. Anodes are virtually always cast in open molds on a large horizontal rotating wheel. Uniformity of anode mass is critical for efficient electrorefining, so most smelters automatically weigh the amount of copper that is poured into each anode mold. The molds are also carefully leveled on the wheel to give parallel anode faces. The cast anodes are often straightened and flattened in automated anode preparation machines. Their lugs may also be machined to a knife-edge. Uniform, straight, flat, vertically hung anodes give pure cathodes, high productivity, and efficient energy use in the electrorefinery. |
