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How to select refractory for reduction furnaces
Jan 10, 2018

There are three types of refractory for reduction furnaces.

1. MgO-C refractory material

2. MgO-Cr2O3 refractory material

3. Al2O3-C refractory material

 

1) MgO-C refractory material

  The main reason for the damage of MgO-C bricks is the melting reaction of MgO aggregate and the decarburization reaction of carbon matrix caused by gas phase, liquid phase oxidation reaction and MgO-C reaction. The erosion first starts from the carbon matrix.The problem with low-carbon MgO-C bricks is their poor resistance to spalling. The solution is to increase the carbon dispersion of the MgO-C bricks.

How to improve the carbon dispersion? There are several options.

1. The thermal shock resistance of carbon-based MgO-C bricks can be improved by using flake graphite to increase the contact area of graphite with MgO particles, separating the magnesia particles to reduce their contact frequency.

2. Reducing the frequency of contact between graphite particles by increasing the graphite dispersion to separate the magnesia particles , the thermal shock resistance of the low-carbon MgO-C bricks is improved.

3. Use nanotechnology, that is, nano-carbon particles, such as carbon black, or a special high residual carbon organic resin as a binder for the production of low-carbon MgO-C brick. The former is evenly distributed in low-carbon MgO-C bricks through the tiny carbon particles in the carbon black, and then the thermal shock resistance of the low-carbon MgO-C bricks is obviously improved. The latter is through the carbon particles obtained when the binding agent magnesia particles completely coated so that the contacts between the magnesia particles are separated by continuous distribution of fine carbon particles, thereby inhibiting the low-carbon after firing MgO-C brick elastic mold increases, so that the rapid increase in strength, anti-spalling performance has also been improved.

4. Adding carbon fibers with a diameter of nanometers to low carbon MgO-C bricks increases the toughness of the MgO-C bricks by changing the direction of the diffusion cracks due to the carbon fiber drawing effect or consuming some energy.

 

2) MgO-Cr2O3 refractory can adapt to the conditions of use of the smelting reduction furnace. The higher the content of Cr2O3, the stronger the corrosion resistance of MgO-Cr2Orefractory.Andin order to extend its service life, the amount of the Cr2O3 of refractory of MgO-Cr2O3had better no less than 30%.

 

3) The erosion mechanism of Al2O3-C carbon brick with low basicity and high FeO slag in high temperature oxidation atmosphere should be the oxidation and decarbonization reaction of carbon matrix and the dissolution and erosion reaction of Al2O3 happen at the same time. These three kinds of refractory have certain restrictions on the conditions of use of the smelting reduction furnace, which need to be solved by further improving the properties and the smelting process of the smelting reduction furnace.

 

The Material Design.

According to the operating conditions of melting reduction furnace and the use of the request, choose refractory materials that can reduce the amount of generated liquid to improve the high temperature performance and corrosion resistance.

The Manufacturing Process.

Through the control of raw material particle composition and distribution, and the control of the corresponding process to enhance the bonding state, and  improve the microstructure to improve the resistance to slag.

Through the incorporation of antioxidants and additives the oxidation resistance and the durability of carbon-containing composite refractory material can be improved, and its strength load can be increased.


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