section_path: Production/Methods
section_name: Methods
paragraph_text: Methods
  
  The great majority of copper ores are sulfides. Common ores are the sulfides chalcopyrite (CuFeS), bornite (Cu FeS) and, to a lesser extent, covellite (CuS) and chalcocite (Cu S). These ores occur at the level of <1% Cu. Concentration of the ore is required, which begins with comminution followed by froth flotation. The remaining concentrate is the smelted, which can be described with two simplified equations:
  
  Cuprous oxide reacts with cuprous sulfide to convert to blister copper upon heating
  
  This roasting gives matte copper, roughly 50% Cu by weight, which is purified by electrolysis. Depending on the ore, sometimes other metals are obtained during the electrolysis including platinum and gold.
  
  Aside from sulfides, another family of ores are oxides. Approximately 15% of the world's copper supply derives from these oxides. The beneficiation process for oxides involves extraction with sulfuric acid solutions followed by electrolysis. In parallel with the above method for "concentrated" sulfide and oxide ores, copper is recovered from mine tailings and heaps. A variety of methods are used including leaching with sulfuric acid, ammonia, ferric chloride. Biological methods are also used.
  
  A significant source of copper is from recycling. Recycling is facilitated because copper is usually deployed in its metallic state. In 2001, a typical automobile contained 20–30 kg of copper. Recycling usually begins with some melting process using a blast furnace.
  
  A potential source of copper is polymetallic nodules, which have an estimated concentration 1.3%.