Magnesia is the term for magnesium oxide (formula: MgO). Magnesia is produced by mining and processing mainly the hard rock mineral, magnesite, which occurs in two main forms: cryptocrystalline and crystalline.
Rarely, magnesia may be produced from other hard rock minerals such as dolomite, brucite, huntite, and serpentinite.
Another commercially important source of magnesia is from chemical processing of seawater and magnesia-rich brines, which produces what is sometimes referred to as synthetic magnesia.
Grades produced include:
· Crude magnesite
· Caustic calcined magnesia (CCM)
· Dead burned magnesia (DBM)
· Fused magnesia (FM)
· Magnesium compounds derived from CCM, eg. magnesium hydroxide, magnesium sulphate.
The source of the magnesia determines critical chemical and physical characteristics of the derived magnesia, such as MgO purity (ranges low to high, 85%-99% MgO), ratio of CaO:SiO2, bulk density, and magnesia crystal size.
The worlds total resource of magnesite, the main source of magnesia, is about 13bn tonnes. Six countries host 92% of this, in descending order: China (26%), North Korea (23%), Russia (21%), Slovakia (10%), Australia (7%), and Brazil (5%).
World magnesia production (derived from the magnesite) is about 8.5m. tpa, and is dominated by China (49%). Other leading producers include Austria, Brazil, Greece, Russia, Slovakia, Spain, and Turkey.
World synthetic magnesia production (derived from seawater, brines) is about 925,000 tpa, from Brazil, Japan, Mexico, the Netherlands, Norway, Republic of Ireland, Russia, South Korea, and the USA.
Leading magnesia producers include:
Each end use requires different specifications of the preferred magnesia form, so there are many different grades of magnesia on the market. Certain magnesite deposits are better suited to produce certain magnesia grades than others.
Crude magnesite: agriculture, glass and ceramics.
CCM: agriculture; environment; cement; abrasive binder; pulp and paper; fillers; feedstock for DBM, FM, and magnesium compound production.
FM: refractories; steel coatings; ceramics.