Refractory materials for furnace walls and furnace bottoms

General requirements for refractory materials for electric arc furnaces

The general requirements for refractory materials of electric arc furnaces are:

①High refractoriness: the arc temperature is above 4000℃, the steelmaking temperature is often 1500～1750℃,

Sometimes even as high as 2000 ℃, therefore, the refractory material must have high refractoriness.

②High load softening temperature: The electric furnace steelmaking process works under high-temperature load conditions, and

the furnace body is subject to the erosion of molten steel, so the refractory material must have a high softening temperature under load.

③Good thermal stability: The temperature of electric furnace steelmaking changes sharply within a few minutes from tapping to charging.

The temperature drops suddenly from about 1600°C to below 900°C, so the refractory material is required to have good thermal stability.

④ Good slag resistance: In the steelmaking process, slag, furnace gas, and molten steel have strong effects on refractory materials.

Chemical attack, so the refractory material should have good slag resistance.

⑤High compressive strength: The electric furnace lining is impacted by the charge when charging, and is subjected to the static pressure of molten steel during smelting.

It is scoured by the steel flow when tapping and mechanically vibrated during operation, so the refractory material must have high compressive strength.

③ Low thermal conductivity: In order to reduce the heat loss of the electric furnace and reduce the power consumption, refractory materials are required

The thermal conductivity is poor, that is, the thermal conductivity is small.

Refractory materials for furnace walls and furnace bottoms

(1) Magnesia:

The main component is magnesium oxide (MgO ≥85%), and also contains a small number of impurities (such as SiO:

and CaO, etc.). The higher the magnesium oxide content, the better, and the lower the impurity content, the better. Too high SiOz content

It will reduce its refractoriness, and if the CaO content is too high, it will be easily hydrolyzed and pulverized. The magnesia used in the electric furnace is first-grade metallurgical magnesia. Its ingredients are as follows:

(2)Dolomite:

The main components are calcium oxide and magnesium oxide, which are as follows:

The refractoriness of dolomite is also above 2000℃, it can resist the erosion of alkaline slag, and it is thermally stable

The property is better than magnesia, but dolomite is easy to absorb water and pulverize, so try to shorten the time from firing to using dolomite as much as possible time used.

(3)White quartz sand:

Quartz sand is one of the main materials for the lining of acid electric arc furnaces.

Furnace slope is also used as a repair material for acid electric arc furnaces.

Pure quartz sand is a crystal transparent body, white when it contains a small number of impurities, the more impurities

The darker the gray, the more quartz sand used in electric furnaces is mostly white.