Video #1
Electrolysis
Electrolysis is the process by which an electric current is passed
between two electrodes through an ionic solution, in order to deposit cations
on the negative electrode and the anions on the positive electrode, and
therefore separate a mineral from its ore.
Magnesium
Magnesium, an alkaline earth metal and one of the most abundant
elements dissolved in seawater, is not found naturally as a free element as it
is highly reactive and therefore extremely flammable. Magnesium is placed high
in the reactivity series, and consequently, is refined through
electrolysis. Although the process of
electrolysis is expensive and consumes an enormous amount of electrical energy,
it is the most efficient, reliable and thorough means of separation for
magnesium.
Video #2
Magnesium
Ores and Mines
Magnesium is found as ores in large deposits of Magnesite, Dolomite,
and Brucite, yet is most commonly found dissolved as a solution in seawater and
natural brines in Lake Cargellico, Lake Cobar and Lake Nyngan in New South
Wales.
Extracting
and Refining Process
Through the process of electrolysis, magnesium metal is extracted
from dissolved ions within seawater or magnesium-rich brines. Calcium Magnesium
Carbonate is added to this seawater to produce magnesium hydroxide, which in
turn is used to create Magnesium Oxide. Magnesium Chloride is produced by
heating this magnesium oxide with Hydrochloric Acid. This magnesium chloride which
must heated until it is molten before it is able to conduct electricity. As the
direct current, along with a graphite anode and steel cathode, is placed within
the molten electrolyte, chlorine ions lose electrons to form chlorine anions
which are attracted to the anode and are separated from the magnesium chloride.
Magnesium ions gain electrons to form magnesium cations, which is attracted to
the negatively charged cathode. Therefore Magnesium ions are deposited as a
pure and refined metal.
Video #3
Uses in
Society
·
Used in aircraft, car engine casings, and missile
construction, magnesium alloyed with aluminium are exceptionally versatile as
they are high-strength, and corrosion-resistant alloys. Because magnesium burns brightly, it is used
in flares, fire-starters and fireworks.
·
Magnesium compounds such as its hydroxide and
sulfate are used for medicinal, agricultural and therapeutic purposes.
Magnesium
Depletion?
Making up 13% of the Earth’s mass and mantle, magnesium is
primarily extracted from seawater and magnesium-rich brines. Due to this fact
alone, there is no specific nor estimated time in which Australia nor will the
world find itself in a shortage of magnesium. However, Magnesium found as ores face
possible exhaustion form natural reserves by 3024.
Magnesium ore depletion can deterred and/or avoided by not only
sourcing magnesium from its dissolved state in seawater, but also recycling
magnesium metal and its various aluminium alloys, rather than mining for it.
Australian Government (Geoscience Australia). 2012. http://www.australianminesatlas.gov.au/education/fact_sheets/magnesium.html (accessed 11, 14, 15/Aug/2014)
University of York. 2014. http://www.essentialchemicalindustry.org/metals/magnesium.html (accessed 15/Aug/2014)
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