Sunday, August 17, 2014
Electrolysis
Magnesium
Magnesium, along with its various alloys have a high corrosion
resistance and
boiling/melting temperature (650 °C). Like
its chemically and physically closer companions of potassium, sodium and calcium, magnesium is placed
high in the reactivity series, and consequently, pure magnesium metal highly unstable
and thus is able to be aggressively burned
in nitrogen, carbon dioxide and water, violently reacting with a
characteristically bright white-light. Magnesium also reacts exothermically
with most acids, producing magnesium chloride and hydrogen gas.
Due to its unstable and highly
reactive nature, magnesium is refined through the process of electrolysis,
whereby it is separated and extracted from its ore or solute form. A metallic object which violently reacts in contact with water and acids, magnesium's physical and chemical composition enforce the need for magnesium ores (or seawater solution) to be extracted through electrolysis.
Magnesium cannot be extracted through the process of smelting as it is far too reactive. Being a
metal that is above carbon in the reactivity series, magnesium could be displaced
by a much reactive metal (ie. Potassium or sodium), but this process in much dangerous and expensive than electrolysis, and is thus only used in dire
circumstances. Although the process of electrolysis is expensive and consumes
an enormous amount of electrical energy within the process, it is the most
efficient reliable and thorough means of separation for magnesium, and therefore a
desirable means of its extraction.
Magnesium cannot be extracted through the process of smelting as it is far too reactive. Being a
metal that is above carbon in the reactivity series, magnesium could be displaced
by a much reactive metal (ie. Potassium or sodium), but this process in much dangerous and expensive than electrolysis, and is thus only used in dire
circumstances. Although the process of electrolysis is expensive and consumes
an enormous amount of electrical energy within the process, it is the most
efficient reliable and thorough means of separation for magnesium, and therefore a
desirable means of its extraction. Magnesium Ores and Mines
 |
| Magnesite |
Magnesite and Magnesium in solution can be
found in deposits and lakes throughout Australia, including the
Kunwarara deposit, north-west of Rockhampton in Queensland (Magnesite) ; Thuddungra,
northwest of Young in New South Wales (Magnesite) ; and Lake Cargellico and Cobar in New South
Wales (Magnesium in solution).
Extracting and Refining Process
Through the process of electrolysis, magnesium metal is extracted from dissolved ions within seawater or magnesium-rich brines.
Electric Furnace
Production of Magnesium Chloride from Seawater
To extract the magnesium,
dolomite (Calcium Magnesium Carbonate) is added to magnesium-rich seawater to form a
magnesium hydroxide precipitate and calcium hydroxide in solution. This
magnesium hydroxide (otherwise known as Brucite), is filtered off from the
solution to create magnesium oxide (Magnesia). Magnesium Chloride is produced by heating this
magnesium oxide, combined with carbon, water and chlorine (Hydrochloric Acid).
This solid magnesium chloride is used to obtain pure magnesium in its metallic
state through the process of electrolysis
.
 |
Electrolysis
Electrolysis of Magnesium Chloride
In the process of electrolysis, solid Magnesium Chloride must be melted be heated until it is molten before it is able to conduct electricity. This
process separates the molten ionic compound into magnesium and chlorine ions as
individual entities and elements.
As the direct current, along with a graphite anode and steel
cathode, is placed within the molten electrolyte, chlorine ions, having a
greater electro-negativity than magnesium, lose electrons (oxidation) to form
chlorine atoms (chlorine anions). The anions are attracted to the positively
charged electrode (anode) and extracted from the electrolytic cell as chlorine
gas.
 |
Uses in Society
- Accounting for 50% of the total magnesium metal consumption, the alloying of magnesium with aluminium is the most common use of magnesium.
- With a density of only two-thirds that of aluminium, and one-fifth that of iron, magnesium alloys are exceptionally versatile and used in aircraft, car engine casings, and missile construction.
- The addition of magnesium to aluminium produces high-strength, corrosion-resistant alloys.
- Magnesium is used as an agent in the refining and production of titanium and uranium.
- Because magnesium burns brightly, it is used in flares, as fire-starters flashbulbs, and fireworks.
- Magnesium is also used in some dry-cell batteries and photoengraving.
- Magnesium compounds such as its hydroxide (milk of magnesia), sulfate (Epsom salts), chloride and citrate are used for medicinal purposes.
 |
| Magnesium Flares and Fireworks |
 |
| Magnesium Sulfate is used for various medicinal, agricultural and therapeutic purposes |
Magnesium Depletion?
Seeing as though magnesium is one of the most abundant element upon land and in water, making up 13% of the Earth’s mass and mantle, magnesium is primarily extracted from seawater and magnesium-rich salt brines, and it therefore seems highly improbable that Australia’s natural magnesium reserves will deplete in the foreseeable future. Due to this fact alone, there is no specific nor estimated time in which Australia nor the world will find itself in a shortage of magnesium.
However, an excessive and unnecessary amount of magnesium ore mining, extraction and exploitation will result in its deficiency in our soil, but not so within our waterways and systems. Magnesium found as ores through open-cut mining (ie. magnesite and dolomite) face possible exhaustion form Australia's natural reserves by the year 3024. This figure, however can be altered through society's utilisation of magnesium in its natural state. Using magnesium sourced from seawater and brines is the only secure manner of using and producing magnesium for the benefit of humanity. Therefore, in order to sustain our magnesium reserves, it would seem wise to only produce magnesium alloys and ores from dissolved magnesium in water, rather than mining for it. Extracting magnesium from our waterways rather than soils will deter any chances of potential deletion and therefore allow society to continue in using magnesium as a metal and an alloy.
Magnesium, in its dissolved state in seawater and brines, does not face any means of depletion, yet magnesium found as ores within the crust and mantle do. Magnesium ore depletion can deterred and/or avoided by not only sourcing magnesium from salt-water, but also recycling magnesium metal and its various aluminium alloys.
However, an excessive and unnecessary amount of magnesium ore mining, extraction and exploitation will result in its deficiency in our soil, but not so within our waterways and systems. Magnesium found as ores through open-cut mining (ie. magnesite and dolomite) face possible exhaustion form Australia's natural reserves by the year 3024. This figure, however can be altered through society's utilisation of magnesium in its natural state. Using magnesium sourced from seawater and brines is the only secure manner of using and producing magnesium for the benefit of humanity. Therefore, in order to sustain our magnesium reserves, it would seem wise to only produce magnesium alloys and ores from dissolved magnesium in water, rather than mining for it. Extracting magnesium from our waterways rather than soils will deter any chances of potential deletion and therefore allow society to continue in using magnesium as a metal and an alloy.
Magnesium, in its dissolved state in seawater and brines, does not face any means of depletion, yet magnesium found as ores within the crust and mantle do. Magnesium ore depletion can deterred and/or avoided by not only sourcing magnesium from salt-water, but also recycling magnesium metal and its various aluminium alloys.
The Electrolysis of Magnesium Chloride: TRANSCRIPT
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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