COPPER
In prehistory, copper could be
found as native copper on the surface of the ground. Prospecting
for copper in this environment was relatively simple. Over time,
increased demand has meant that mining has turned to more
marginal forms of copper to continue supply. These marginal
copper sources are also much more difficult to locate. When a
copper body is discovered, drilling is undertaken to determine
the size of, and proportion of copper in the orebody zones
(called the grade of copper).
As of
2005 Chalcopyrite ore is extensively mined in
Chile,
the
United
States,
Canada,
Zambia,
Kazakhstan,
Mauritania and
Poland.
In the United States, the states of
Arizona,
Montana,
New
Mexico, and
Utah
lead in ore mining. Indeed, the world's largest copper mine, the
Chuquicamata, is located in
Atacama,
Chile.
Most copper currently is mined
from large
open
pit mines that contain 0.4 to 1.0 percent
copper. Examples include:
Chuquicamata in
Chile
and
El
Chino mine in
New
Mexico.
EXTRACTING COPPER
First the copper ore from a open pit mine is
blasted, loaded and transported to the primary crushers. Then the ore is crushed
and screened, with the fine sulphide ore going to froth flotation cells for
recovery of copper. The coarser ore goes to the heap leach, where the copper is
subjected to a dilute sulphuric acid solution to dissolve the copper. Then the
leach solution containing the dissolved copper is subjected to a process called
solvent extraction (SX). The SX process concentrates and purifies the copper
leach solution so the copper can be recovered at a high electrical current. It
does this by adding a chemical reagent to the SX tanks which selectively binds
with and extracts the copper. The concentrated copper solution is dissolved in
sulphuric acid and sent to the electrolytic cells for recovery as copper plates
(cathodes). From the copper cathodes, it is manufactured into wire, appliances,
etc. that are used in every day life.

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.

Banks of electrowinning cells with cathodes.
Copper on the anodes 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.
HISTORY
In Greek times, copper was known
by the name chalkos (χαλκός). Copper was a very important
resource for the Romans and Greeks. In Roman times, it became
known as aes Cyprium.
Copper was known to some of the
oldest civilizations on record, and has a history of use that is
at least 10,000 years old. A copper pendant was found in what is
now northern Iraq that dates to 8700 BC. By 5000 BC there are
signs of copper smelting, the refining of copper from simple
copper oxides such as malachite or azurite. There are copper and
bronze artefacts from Sumerian cities that date to 3000 BC.
The Egyptians found that adding
a small amount of tin made the metal easier to cast, so bronze
alloys are found in Egypt almost as soon as copper is found. Use
of copper in ancient China dates to at least 2000 BC. By 1200 BC
excellent bronzes were being made in China. In Europe, Oetzi the
Iceman, a well preserved male dated to 3200 BC, was found with a
copper tipped axe whose metal was 99.7% pure. High levels of
arsenic in his hair suggests he was involved in copper smelting.
Copper was associated with the
goddess Aphrodite/Venus in mythology and alchemy, owing to its
lustrous beauty, its ancient use in producing mirrors, and its
association with Cyprus, which was sacred to the goddess.
THE ELEMENT
|
Symbol: |
Cu
|
|
Atomic Mass: |
63.546 |
|
Atomic Number: |
29
|
|
Melting Point: |
1083
°C |
|
Boiling Point: |
2567
°C |
|
Density in Natural State:
|
8.92
g/cm3 |
|
Natural Abundance: |
70
parts per million |

structure of a copper atom
USES OF COPPER

Copper is
malleable
and
ductile,
and is used extensively, in products such as:
- Copper
wire.
- Copper
plumbing.
- Doorknobs
and other fixtures in houses.
-
Statuary:
The
Statue of Liberty,
for example, contains 179,200 pounds (81.3
tonnes)
of copper.
-
Electromagnets.
-
Motors,
especially electromagnetic motors.
- Electrical
relays,
electrical
busbars
and electrical
switches.
-
Vacuum tubes,
cathode ray tubes,
and the
magnetrons
in
microwave ovens.
- There is
increasing use of copper in
integrated circuits,
replacing
aluminium
because of its superior conductivity.
- Alloyed
with
nickel,
e.g.
cupronickel
and
Monel,
used as corrosive resistant materials in
shipbuilding.
- As a
component of
coins,
often as cupronickel alloy.
- In
cookware,
such as
frying pans.
- Most
flatware
(knives,
forks,
spoons)
contains some copper (nickel
silver).
-
Sterling silver,
if it is to be used in dinnerware, must
contain a few percent copper.
- As a
component in ceramic
glazes,
and to colour
glass.
-
Musical instruments,
especially
brass instruments.
-
Copper(II) sulfate
is used as a poison and a water purifier. It
is used in gardening powders and sprays to
kill
mildew.
- As a
material in the manufacture of computer
heatsinks,
as a result of its superior heat dissipation
capacity to
aluminium.

Crazy Facts Corner
- Copper
doorknobs
are used by
hospitals
to reduce the transfer of disease, and
Legionnaire's
Disease is suppressed by copper tubing in
air-conditioning
systems.
- The Statue of Liberty is made of copper.
It is green because the copper has reacted with the carbon dioxide in the
air.
- A piece of copper
tubing from 5,000 years ago was unearthed by archaeologists from the Pyramid
of Cheops in Egypt.
- The sixth wonder of the
world was the Colossus of Rhodes, a huge statue of Helios the sun-god, made
of bronze (90% copper, 10% tin) and reinforced with iron and weighted with
stones.
- Copper and brass are
easily recycled - perhaps 70% of the copper now in use has been recycled at
least once.
- An average family home
contains more than 90 kilograms of copper: 40 kg of electrical wire, 30 kg
of plumbing, 15 kg of builders hardware, 9 kg inside electrical appliances,
and 5 kg of brass goods.
- A Boeing 747-200 jet
plane contains about 1.8 tonnes of copper.
Links:
http://www.mine-engineer.com/mining/copperm.htm
http://en.wikipedia.org/wiki/Copper
http://web1.caryacademy.org/chemistry/rushin/StudentProjects/ElementWebSites/copper/basic_info.htm
http://www.copper.com.au/cdc/article.asp?CID=58&AID=268
Researched by Angua-
|