Chemistry Open Book Paper - Extracting Copper From Its Ore.

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CHEMISTRY OPEN BOOK PAPER

Extracting Copper from its ore.

Low-grade ore is piled on specially treated impermeable ground for ease later to drain away the Cu ion solution. The bacteria can then be sprayed on requiring acidic conditions, a supply of Fe2+ and S2- ions, oxygen; carbon dioxide; and nitrogen and phosphorous containing nutrients. Thiobacillius ferro-oxidans and Thiobacillius thio-oxidans, gain energy to live by oxidising Fe2+ ions and S2- ions respectively. In effect they release the required metal ions into solution.

The copper ion solution can now be drained off and the copper ions removed using another solvent in a Ligand Exchange Reaction.

Ligand = compound with a lone pair of electrons which binds with metal compounds to form a complex. [2]

The ligand can be dissolved in an organic solvent (such as kerosene) which is immiscable in water.

Cu2+(aq)   + 2LH (organic)                                      CuL2 (organic)  + 2H+ (aq)

The copper is removed from a low concentration in water to a high concentration in the organic solvent.

By adding concentrated acid to the organic solvent the process can be reversed – Cu2+ ions go back into the aqueous therefore further increasing the concentration of the Cu2+ ions.

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By passing an electric current through the copper ion solution the copper can be extracted in sheets. Pure copper collects on the negative electrodes. [3]

EXTRACTING GOLD FROM ITS ORE.

Crushing and Grinding. This reduces the chunks of gold to fine grains. A crusher first commences to break the fragments to the size of road gravel. A cyanide solution is then mixed with the fragments. “A rotating ball mill reduces the fragments to form a pulp. Any coarse particles will be returned ...

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