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Cement Refractories

Nedmag is one of the few producers in the world capable of producing DBM with a purity close to 99%. Most DBM suppliers do not get beyond a purity of 97%. High purity leads to better refractory properties.

 

 purity :

  • high magnesia oxide content

  • low lime content

  • zero free lime content

  • low level of impurities

 

The absence of free lime results in a highly hydration-resistant product. Both the magnesia sinter and the magnesia spinel brick made from  have a long storage life. The composition of  is also beneficial due to a high lime/ silica ratio and a low and properly controlled boron level (0.01% B2O3) which prevents the formation of low melting phases in the magnesia and extend the life time of refractories.

 

 microstructure:

  • high density: minimum 3.40g/cm3

  • very homogeneous microstructure due to the synthetic process

  • low porosity and homogeneous distribution of small pores

  • optimum crystal size: 70 µm

 

Using , you can produce magnesia spinel bricks for the rotary kiln which can withstand the highest levels of mechanical, chemical and thermal stress.

Thermal stress can be caused by local overheating, especially in the first lining zones, when using alternative fuels. This has a weakening effect on the integrity of the refractory brick. The effect is reduced by using  nedMag 99 with a high magnesium oxide content (98.5% MgO), a low silica content (0.12% SiO2) and a lime/silica ratio  of >4:1. This high lime silica ratio prevents the formation of low melting phases. The optimal crystallography of  results in a less brittle refractory brick which is better resistant against thermal shocks and an increased the life time of the refractory lining

Chemical stress created by corrosion can lead to a weak microstructure and to spalling of the magnesia spinel brick. Mag-spinel bricks with   inside have a low permeability due to the very homogeneous microstructure with a low amount of closed porosity. This gives a higher resistant against gas- and alkali infiltration. A  magnesia spinel based brick is not sensitive to the formation of low melting calcium aluminate phases in the lining of the rotary kiln during clinker production. The best product when using alternative fuels.

Mechanical stress like erosion may lead to abrasion of the magnesia spinel brick. A high lime/silica ratio promotes the formation of high melting di-calcium silicates (2.130 °C). High melting phases increase the abrasion resistance of the brick. Using   with a high magnesium oxide content and high lime/silica ratio (>4:1) results in less abrasion of the magnesia spinel brick in the rotary kiln. The optimal crystallography gives the brick more elasticity

 has a high density of minimum 3.40 g/cm3 and a very homogeneous microstructure with very small pores. This results in magnesia spinel bricks with a very low permeability which limits gas -and alkali infiltration. This gives a longer life under severe conditions especially where alternative fuels are used.

Due to the synthetic production process, Nedmag is able to produce a product with a very consistent composition. This makes  easy to handle in the production process of the magnesia spinel bricks.

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