carbon blast furnace refractory material
Advantages and disadvantages of carbon blast furnace refractory material
The main carbon refractory material used for blast furnace are carbon brick, graphite carbon brick, graphite silicon carbide brick, self-bonding or nitrogen-bonded silicon carbide brick and ramming materials.
(1) Characteristics of carbon refractory for iron making
1) Carbon refractory is the ideal refractory for blast furnace lining, it has the following advantages:
① Carbon refractory has high refractoriness, it will neither melts nor soften in blast furnace.
② Carbon refractory’s thermal expansion coefficient is small, it has a good volume stability in large temperature range.
③ Carbon-saturated molten iron will not erode carbon brick, in certain cooling condition, the corrosion of the slag to the Carbon lining is also small.
④ Carbon refractory has high thermal conductivity and electrical conductivity, using carbon refractory in the furnace bottom and hearth can make cooler play full performance, thereby extending the life of furnace lining material to prevent burning through.
⑤ Carbon refractory has excellent cutting performance, it can be made into shaped products in a very small size to meet the masonry requirements.
2) The biggest drawback of carbon refractories is that carbon and graphite burn in oxidizing atmosphere. When temperature reaches 700℃, carbon refractories begin react with carbon dioxide, and 500℃ it will react with water, and higher than 400℃ it will be oxidized. So for carbon brick’s exposed part, a protective layer should be built.
(2) Silicon carbide brick
Silicon carbide brick is a kind of inert material, it has good thermal conductivity, small expansion coefficient, high temperature strength, small creep deformation, and also silicon carbide brick has good anti-slag, anti-iron scouring and corrosion resistance, besides, silicon carbide’s oxidation resistance is better than carbon materials. The main problem is to find a combination of alkali-resistant metal corrosion. Also useful in nitride-bonded or self-bonded silicon carbide refractories. To extend the life of lower part of furnace, it is better to use silicon carbide brick.
(3) Aluminum carbon brick
Blast furnace aluminum carbon brick uses high quality bauxite and graphite as main raw material, being added a small amount of silicon carbide and additives, using resin as binder, and finally burnt through a compression-molding process. Aluminum carbon brick has the characteristics of high temperature resistance, good thermal conductivity, good alkali resistance, low porosity, small dimensional deviation and low price. It can be used in blast furnace heart, furnace waist, furnace body, iron mouth area, bottom of the furnace and other parts.
The characteristics of unshaped refractory are as follows.
Compared with shaped refractory, due to can celled the complex firing process, unshaped refractory’s production process is simpler, it is easy to use. Unshaped refractory has the advantage of plasticity, easy complex product molding, and conducive to mechanized construction, and low cost, and unshaped refractory’s using life is similar to that of refractory bricks. Its refractoriness and chemical stability is close to or can reach the level of similar refractory bricks. Besides, unshaped refractories can be prefabricated into large pieces.