Current Energy Requirements in the Copper Producing Industries

Summary

An analysis of energy usage in the production of refined cathode copper was made from mining ore to cathode copper. In mining copper ore the greatest energy consumers are ore hauling and blasting. Another important factor is the “recovery efficiency” of the metallurgical processes used to extract the copper. The mining and mineral concentrating energies are directly proportional to the “recovery efficiency,” with a typical mining operation requiring about 20 million Btu/ton of cathode copper produced. Mineral concentrating was also found to be a large energy consumer, requiring about 43 million Btu/ton of cathode copper. Some possibilities for energy savings in the mineral processing area include use of autogenous grinding and computer control for optimizing grinding operations, improved classifier efficiency, and optimizing the entire concentrator plant performance by interrelating all plant operations.

In acid plants, optimization of input SO₂ concentration can make the plant a net producer rather than a net user of energy. The conventional smelting process utilizes very little of the energy from the combustion of sulfides in the charge. Several of the newer copper pyrometallurgical processes which utilize more of the combustion energy of the sulfides as heat show a significant improvement over conventional smelting. Generally, increased use of oxygen decreases Level 1 energies but proportionately increases Level 2 energies.

Hydrometallurgical processes are, in general, more energy intensive than smelting processes, mainly because of the inability to utilize the heat of reaction of the sulfides. Electrowinning used in most hydrometallurgy processes is also energy intensive, and research in these areas could produce significant energy savings. Combination pyrometallurgical processes are generally less energy intensive than entirely hydrometallurgical processes. Significant improvements may be made in energy use in hydrometallurgical processes by more effective waste heat recovery, new electrowinning technology, and combined hydrometallurgical and pyrometallurgical low energy consumption unit processes.