Copper Mining

1. Copper Mining What are Copper Ores? Ores are samples of earth that contain specific rocks and minerals composed of desirable elements combined with less useful waste materials. What is a mineral? A mineral is (generally) an inorganic, naturally occurring, organized crystalline structure composed of a single chemical compound or element. What is a rock? A rock is (generally) a natural solid composed of multiple crystals of one or more minerals. Although many rocks contain visible crystals of individual minerals, a rock itself does not have an overall crystalline structure.

2. Crystals form because their component chemicals tend to aggregate together in certain specific arrangements dictated by the shapes and components of the molecules involved. Often, minerals are formed as a solution changes in some way which allows or forces the component mineral(s) to solidify. This change may be caused by changes in temperature, pressure, chemistry, or concentration. A slow solidification or precipitation supports the growth of larger crystals. Note that this process is responsible for much of the mineral segregation that gives us ores, as well as all of the gemstones we admire.

3. The mineral Cuperite is a copper oxide mineral, with as much as 88% copper content. Although it's copper content is high, it is not a major source of copper, because it is not normally present in large quantities. Its occurance is sporadic and infrequent.

4. Chalcopyrite is a copper ore and the primary copper source. When exposed to the elements it will tarnish (oxidize) to various shades of blue and purple, and is often iridescent. It can contain small amounts of gold, silver, selenium, thalliun and arsenic, as well. Many large copper producers are also major gold producers because of cahlcopyrites gold content.

5. Malachite is a copper bearing mineral, with as much as 58% copper content. Malachite is a common but minor ore of copper. It is usually found in copper deposits associated with LIMESTONE, occurring with AZURITE as the weathering product of other copper ore minerals. Malachite forms needlelike prismatic crystals (monoclinic system) that are rarely distinct; it is usually found in granular, earthy, or fibrous masses and rounded, banded crusts. Malachite is used as a decorative stone when cut and polished, a semiprecious gem, and a green pigment.

6. Half of the world's copper deposits are in the form of chalcopyrite ore. All important copper-bearing ores fall into two main classes: oxidized ores and sulfide ores. Ores are removed either by open-pit or by underground mining. Ores containing as little as 0.4% copper can be mined profitably in open-pit mining, but underground mining is profitable only if an ore contains 0.7%-6% copper. The oxidized ores, such as cuprite and tenorite, can be reduced directly to metallic copper by heating with carbon in a furnace, but the sulfide ores, such as chalcopyrite and chalcocite, require a more complex treatment in which low-grade ores have to be enriched before smelting begins.

8. Copper Ore being loaded into a 300 ton truck for transport to the crusher.

9. The primary crusher at a copper mine. The truck dumps ore into the crusher which crushes the ore. Screens size and distribute the classified ore to a series of conveyors, like those above, for transportation to the mill for further processing.

11. Conveyors and trucks deposit coarse ore on a heap leach pad, which has a series of pipes and hoses dispensing a diluted sulfuric acid solution to the ore. Copper is dissolved and flows to a pond at the bottom of the pad. This process can take several months. The leached solution is pumped to the SX (Solvent Extraction) circuit, which looks like a series of agitation tanks or cells. The fine sulfide ore is sent to froth flotation cells like those below for recovery.

12. The froth flotation cells recover the copper from sulfide ores by chemically attaching the copper to a chemical bubble and overflowing the froth (bubbles with copper).

13. Banks of electrowinning cells with cathodes. Copper on the annodes ranges from 99.0 to 99.5 percent pure. Power consumed in electroplating copper ranges from 0.08 to 0.20 KWH per pound of copper. Any gold or silver in the copper does not plate out and drops to the bottom of the cell with the sludge to be recovered later.

14. Machine transporting and handling the copper cathodes that were removed from the electrowinning cells. That's it, the rest is manufacturing products from the pure copper!