Sea Water to Metal: Examining the Sustainable Future of Magnesium Production

 

Magnesium Metal

Magnesium is the third most abundant structural metal in the human body and eighth most abundant element in the Earth's crust. It is also the lightest structural metal and an essential mineral for human and animal health. Magnesium is essential for activating more than 300 enzymes in the human body and plays a vital role in many biochemical reactions involved in energy production and protein synthesis. Magnesium metal is also widely used in industries due to its light weight, high specific strength and resistance to corrosion. This article explores the various properties of magnesium metal and its uses in industries.

Physical and Chemical Properties

Magnesium metal is a silver-white, lightweight metallic element with the atomic number 12. Some key physical and chemical properties of magnesium include:

- Density: Magnesium has a density of 1.738 g/cm3 which is much lower than common structural metals like iron and aluminium. This makes it the lightest structural metal.

- Melting Point: Magnesium has a relatively low melting point of 649°C which allows it to be easily cast and welded.

- Atomic Structure: Magnesium has an hexagonal close-packed crystalline structure which gives it combined properties of strength and ductility.

- Reactivity: Magnesium is highly reactive and corrodes rapidly in air. A thin layer of oxide typically forms on its surface to protect it from further corrosion. It burns with a brilliant white light when ignited.

- Alloying: Magnesium forms many useful metallic alloys when combined with aluminium, zinc, manganese and other rare earth elements. These alloys exhibit improved strength, ductility and corrosion resistance.

Occurrence and Production

Magnesium comprises about 13% of the Earth's crust mass and is the eighth most abundant element here. It rarely occurs in its native form in nature due to its high chemical reactivity. The principal ores of magnesium are magnesium carbonate (MgCO3), silicate (MgSiO3) and chloride salts.

Major deposits of magnesium ores exist in China, Russia, Canada and Israel. Seawater is also a potential unlimited source of magnesium containing approximately 1.3 kg of magnesium per cubic meter of water.

The two main industrial processes for producing magnesium metal are:

1) Pidgeon Process: In this process, magnesium chloride or carnallite is treated with sodium to produce Magnesium Metal via electrolysis.

2) Allied-Signal Process: Involves magnesium extraction from seawater using the dolime-soda process. The extracted magnesium chloride is then electrolyzed to yield magnesium metal.

Applications of Magnesium Metal

Automotive Applications

- Due to its light weight, over 50% of the magnesium produced globally is used in the automotive industry for manufacturing engine blocks, steering wheels, casings and other auto components. This reduces the overall vehicle weight and improves fuel efficiency.

- Several carmakers now use magnesium alloy parts in seats, door panels, consoles etc. to achieve weight savings.

Aerospace Applications

- Magnesium alloys are widely used in aircraft structural components like wings, fuselages and rotor blades to reduce flight weight. This improves flying performance and range of aircrafts.

- Spacecrafts also employ magnesium for satellites, launch vehicles and space structures again due to their light weight.

Electronics Applications

- Thin magnesium sheets are commonly used as housing and structural parts in laptops, smartphones, tablets etc. to reduce device weight and improve portability.

- Magnesium alloys with rare earth elements find application in manufacturing housings for magnetic resonance imaging (MRI) machines.

Other Applications

- Sports goods like bicycles, golf clubs use magnesium alloys to provide light weight strength.

- Magnesium castings are used to make decorative pieces and for machine tool beds where weight reduction and vibration damping are important.

- Magnesium powder acts as a desulfurizer in steelmaking and is also used as an ignition agent in fireworks.

In summary, magnesium metal is an irreplaceable light weight structural material with a multitude of industrial applications. Its high specific strength and corrosion resistant alloys make it well suited for use in automotive, aerospace and electronics sectors. With the increasing focus on fuel efficiency and reduced emissions, magnesium is expected to play an even more vital role in designing light weight transport systems of future. Its production needs to be optimized further to satisfy growing global demand in the years to come.

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