Talk:Copper concentrate

How are oxides & sulfides separated? Josh Parris 07:16, 4 Mar 2005 (UTC)

Copper ore deposit geology

To a large extent, copper oxide and sulfides are naturally separated in nature:

Copper orebodies are formed when geothermal solutions bring copper dissolved from deep underground near the surface and cool into rock.

Copper is usually deposited as copper sulfides or copper metal. During millions of years the mineral deposit may be exposed to oxygen by air penetration, or by oxygen rich water flowing over it. This oxidation alters the mineralogy, changing the minerals from sulfides to sulfates as sulfate in solution. Beneath this oxide zone, some disolved copper enriches the sulfies, making a secondary enrichment, or transitional zone. The primary enrichment was caused by the superheated geothermal solutions. The secondary enrichment replaces iron in the minerals with more copper, further enriching the ore.

Therefore, typical copper ore deposits are described in terms of their oxide, secondary and primary ore tons and grades.

This is a list of common copper minerals.

1. Oxides

• Aracamite Cu2Cl(OH)3
• Azurite 2CuCO3Cu(OH)2
• Cuprite Cu2O
• Chrysocolla CuSiO32(H2O)
• Malachite CuCO3Cu(OH)2
• Native Copper Cu
• Tenorite CuO

1. Secondary Sulfides

• Chalcocite Cu2S
• Covellite CuS

1. Primary Sulfides

• Bornite Cu5FeS4
• Chalcopyrite CuFeS2

Oxide ores are readily leached by sulfuric acid, usually using a heap leach or dump leach process in combination with solvent extraction and electrowinning technology (SX-EW). There have been examples where froth flotation was used to concentrate malachite. In general froth flotation is not used to concentrate copper oxide ores, as the cost of leaching is cheap when compared to the cost of grinding and flotation.

Secondary sulfides are resistent to sulfuric leaching, and so can be termed refractory. High grade secondary sulfides may be concentrated using froth flotation, and subsequently smelted to recover the copper, or else they can be leached using a bacterial oxidation process to oxidize the sulfides to sulfuric acid, which also allows for simultaneous leaching with sulfuric acid. Again, solvent extraction and electrowinning technologies are used to recover the copper from the pregnant leach solution.

Primary sulfides, most commonly chalcopyrite, are strongly refractory to sulfuric acid and to bacterial leaching technologies. Many competing hydrometallurgical technologies have been developed in the 1990's to treat low grade primary sulfide copper ores, however the pyrometallurgical approach of smelting a froth flotation concentrate is still the only significant industrial process in use.