Refractory materials magnesium oxide

Magnesium oxide has many uses, e.g., in the vulcanization of rubber, as a material for making other magnesium compounds, as an insulating material, as a refractory material, and as an abrasive. 

Pure sintered magnesium oxide ceramics have little importance compared with magnesium oxide-containing refractory products. They are used as high temperature materials. 

An English patent (1906) describes the production of pure tantalum by electrolysis of fused K2TaF7 in a refractory crucible of magnesium oxide or tantalum oxide, using pure tantalum metal as cathode and the impure metal as anode. A French patent (1907) claims that very pure tantalum may be prepared by electrolysis of tantalum material in a 3 per cent solution of H2SO4. The electrodes are platinum or carbon and a current of 0.1-0.3 ampere at two volts is required. 

Boron is also a problem in some areas of industry. Magnesium oxide (MgO) used as a refractory material or magnesium chloride (MgCl2) used to produce magnesium metal must be low in boron. Because of the high atomic cross section of boron, the boron content of many materials of construction and chemicals used in atomic energy must also be extremely low. 

The Chemical Abstract Service has defined these materials under the CAS number 142844-00-6 as Refractories, fibers, aluminosilicates. Amorphous man-made fibers produced from melting, blowing or spinning of calcinated kaolin clay or a combination of alumina (AI2O3) and silica (SiOa). Oxides such as zirconia, ferric oxide, magnesium oxide, calcium oxide and alkalines may also be added. 

Some refractory investment (mould casting) materials are based on the reaction between ammonium dihydrogen phosphate and magnesium oxide which occurs on adding water (12.67). A typical formulation is [40]... 

Magnesium oxide MgO, obtained by calcination of magnesite, is mainly used as a refractory material for lining furnaces for iron and steel production as well as for the manufacture of glass and cement... 

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