Calcined and Dead Burned Dolomite Doloma

Description and general properties. Like other carbonates, upon heating above 900 C dolomite decomposes completely into a mixture of calcium and magnesium oxides, and carbon dioxide  

The product resulting from this relatively low-temperature calcination is highly porous and reactive and is known as calcined dolomite or simply doloma or dolime (i.e., CaO + MgO). Like lime, most dolime is produced either in vertical shaft kilns (Europe and UK) or rotary kilns (USA). Dolime is used in the extractive metallurgy of magnesium metal by the sili-cothermic process. 

Although pure magnesite decomposes at 700 C and calcite at 900 C, dolime is too porous for most refractory uses. Therefore, prior to use it is calcined at a higher temperature of ca. 1700°C. This harsh treatment allows the material to shrink thoroughly and render it less reactive than calcined dolomite. The product obtained is called dead burned dolomite and is generally used for the refractory made by firing dolomite, with or without additives, at high temperatures to produce dense, well-shrunk particles. 

There is another product known as stabilized refractory dolomite. It is manufactured by a process similar to that of Portland clinker. Dolomite and serpentine, with small amounts of 

Industrial applications and uses. Dead burned dolomite exhibits high refractoriness and can withstand temperatures up to 2300 C. It is widely used as a refractory material wherever steel is refined using basic slag. It is used for original hearth installations in open hearth furnaces as well as for hearth maintenance. These hearths are installed using tar-dolomite ramming mixes and rammed dolomite. Dolomite refractories are also used in electrical furnaces and in the cement industry during cHnker manufacture. 

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