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Conditions For The Use Of Carbon Bricks And Graphite Bricks For Blast Furnaces
Jan 18, 2019


The blast furnace lining uses carbon refractory material, which is initially in the hearth of the furnace, and then gradually expands to the belly of the furnace, the lower part of the furnace body, the bottom of the furnace, etc. The carbon refractory (carbon brick) or graphite is mainly used in the belly of the furnace. Bricks (including semi-graphite bricks). However, after clarifying the intrusion of alkali and zinc, CO gas-induced carbon deposition, poor cooling effect, and insufficient wear resistance, a more durable alternative refractory material was developed.

The blast furnace bottom is another important part that determines the service life of the blast furnace. Because the total temperature of this part is about 1600 °C, it is difficult to repair, so the refractory material is more stringent.

The carbon brick for the bottom of the furnace needs to meet the following conditions:

(1) molten iron cannot penetrate into the tissue through the pores (about 1 μm);

(2) Less melting due to molten iron, and no selective erosion within the brick structure;

(3) high thermal conductivity and good cooling effect;

(4) Strong alkali resistance;

(5) Low gas permeability to prevent intrusion of zinc, oxidizing gas, etc.;

(6) The elastic modulus is small, the strength is high, the deformation energy is high, and the heat is shocked.


The carbon/graphite bricks below are the most commonly used carbon refractories in the lower part of the blast furnace:

(1) Standard carbon bricks;

(2) ultra-microporous carbon/graphite bricks;

(3) microporous semi-graphite bricks;

(4) Graphite bricks.

The length of life of the blast furnace depends mainly on the erosion performance of the refractory material of the hearth. Figure 1 shows a typical configuration of a hearth refractory. The performance of representative carbon/graphite bricks (carbon blocks) for furnaces is shown in Table 1.

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