Copper: Outlook in 2011
production, producers, prices, technologies, trends
World mine production of copper was 15.8 million metric tonnes (Mt) in 2009; world reserves are estimated to be 540Mt, 34 years at 2009 rate of production. Twelve countries produced 86% of world production (link). Major sources of copper are found in disseminated form in magmatic rocks near continental plate junctions - principally along the west of the Americas and in central Asia (link). These are porphyry copper orebodies, of very low grade (typically 0.5% Cu or less); these ores are sulphides - the copper bearing minerals are mainly chalcopyrites and bornites. See geology (link).
NB: world demand of refined copper in 2009 was 19Mt. The difference with 15.8Mt is recycling (15% of total) and variations of stocks. Mines and smelters have excesss capacity due to past investments made in anticipation of world growth (on this, more later).
Along the west of the Americas, three major producers of the world are Chile, Peru, the United States in that order, and Mexico (but much smaller); by far the largest producer is Chile (34% of world production). The combined production of the Americas in 2009 was 44% of world production. The US was the biggest producer of copper during the 20th century; technology to extract copper from low grade orebodies was developed there and reserves are diminishing (link).
Because they are very low grade (±0.5%Cu), porphyry copper ores require high levels of concentration to produce materials that can be smelted. Concentrates are 30%+Cu, so the concentration ratio is typically 60. The concentration process is by fine grinding (minus 100μ) and flotation in flotation cells to concentrate the copper bearing sulphide minerals. Great quantities of very fine waste tailings are produced in the process that are disposed of in large tailings ponds protected against spilling to the environment by dams, and where the tailings settle and water evaporates, leaving fine sands.
A smaller percentage of world production is produced in sedimentary copper deposits which result from the weathering of porphry coppers in geologic aeons - from magmatic cratons - later covered by thick sediments. Typical sedimentary copper deposits are found in Poland, Zambia and the Democratic Republic of Congo.