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.

Magnesium ions gain electrons (reduction) to form magnesium atoms (magnesium cations). Pure magnesium metal is attracted to the negatively charged cathode and deposited upon this electrode. Being less dense than the electrolyte itself, liquid magnesium floats on the surface. A physical circulation in the electrolyte is created by the physical motion of the chlorine gas rising to the surface. Therefore a dense pond of magnesium metal is produced and pure magnesium is extracted form the electrolytic cell using a vacuum.