Copper's healthy maintenance of markets and its promise to gain new ones, such as superconductivity applications, new marine uses such as ship hulls and sheathing of offshore platforms, electric vehicles, earth-coupled heat pumps, solar energy (which will inevitably re-emerge at some point when oil supplies tighten), fire sprinkler systems, and nuclear waste disposal canisters, to name a few, must be balanced against its prospects of future availability.
Of the world's reserves of copper about one-quarter of the deposits are economically recoverable now or in the near future. Of this reserve base about 16% (198 billion pounds of copper) is in the USA.
Each year about 3 billion pounds are withdrawn from the earth as US mine production, a barely discernible amount. The copper already mined through history amounts to 700 billion pounds, most still in recycling use.
Interestingly enough, although copper is continuously mined and put into use, the estimated US reserve base has stayed relatively constant in recent years, and has increased fourfold from estimates made in 1952 as new deposits have been found and, even more important, because better extraction techniques have allowed leaner deposits to be added to the reserve base. There is every reason to believe that these dynamics will continue well into the 21st century.
Three other factors will also influence copper supply: US self-sufficiency, energy efficiency and recyclability.
The availability of major domestic deposits makes the USA self-sufficient in copper. This is in stark contrast to aluminum which, despite recent advances in domestic supply due to recycling of beverage cans, has only averaged 20% US self-sufficiency.
There are wide variations in the energy used to recover metals from the earth's crust. Copper ranks near the middle for energy required for extraction-higher than iron, zinc or lead, but at considerable advantage to aluminum, titanium and magnesium, which require much larger quantities of energy to break down the ore (or seawater and brines in the case of magnesium) into metallic form.
For all metals the recycling of scrap is considerably more energy-efficient than recovery from ores, and here copper's high recycling rate-higher than any other engineering metal-makes it the material of choice.
Each year in the USA more copper is recovered and put back into service from recycled material than is derived from newly mined ore. Copper's recycle value is so great that premium-grade scrap normally has at least 95% of the value of primary metal from newly mined ore.
The inescapable conclusion is that copper will continue its 10,000-year history of usefulness many millennia into the future.
1. Flotation Process - The process of separating different minerals by agitating a pulverized mixture of the materials with water, oil, and chemicals. Differential wetting of the suspended particles causes unwetted particles to be carried by air bubbles to the surface for collection.
2. Reverberatory Furnace - A furnace or kiln in which the material under treatment is heated indirectly by means of a flame deflected downward from the roof.
3. Electrolytically Refining - A hexademical change produced by running an electric current through a mineral when molten to produce an electrically conductive medium.
4. Sinter - To cause (metallic powder, for example) to form a coherent mass by heating without melting.