Conventionally, copper is recovered by a pyrometallurgical process known as smelting. In this process copper ore is mined, crushed, ground, concentrated, smelted and refined. The mining, crushing and grinding portions of the processing are extremely energy intensive since the rock must be reduced essentially to talcum powder fineness in order to separate the copper-bearing minerals from it. To be applicable to this process, the ores must contain copper minerals in sulfide form; as mineral such as Chalcocite (Cu2S), Chalcopyrite (CuFeS2) and Covellite (CuS) . In the concentrating operations these minerals are separated from the gangue material of the ore, that might contain as little as 0.5% copper to form a concentrate containing 27 to 36% copper. In the smelting operation, the concentrate is fed to a smelter together with oxygen and the copper and iron sulfides are oxidized at high temperature resulting in impure molten metallic copper (97 to 99%), molten iron oxide and gaseous sulfur dioxide. The impure copper is then purified by electrolytic purification to 99.99% pure copper while the iron oxide is disposed of as slag.

Typically, in this process there is more sulfur dioxide produced by weight than there is copper. Rather than discharge the sulfur dioxide into the air, as was once the practice, the sulfur dioxide is captured and converted into sulfuric acid. In the United States, smelter-produced sulfuric acid amounts to approximately 10% of total acid production from all sources. Prior to the mid-1980s, this by-product sulfuric acid had to be sold to other industries, often at a loss due to the long shipping distances.

Beginning in the mid 1980s a new technology, commonly known as the leach-solvent extraction-electrowinning process or, SX/EW Process, was widely adopted. This new copper technology utilizes smelter acid to produce copper from oxidized ores and mine wastes. Today, worldwide, approximately 20% of all copper produced is produced by this is process. In Latin America, the total is closer to 40% whereas in the United States the total is approaching 30%.