What are the Basic Performance Requirements of Refractory Materials for Steelmaking?

Refractory materials are closely related to the iron and steel metallurgical process, are interdependent, promote each other, and develop together. From the perspective of the development process of iron and steel smelting for more than 100 years, every major change is related to the development of new varieties of refractory materials. For example, the successful development of dolomite refractories has promoted the development of alkaline air converters. In recent years, new technologies adopted in steel smelting, such as large-scale blast furnace high-temperature hot-blast furnace, combined blowing oxygen converter, hot metal pretreatment, furnace refining, and continuous steel casting, have all relied on the development of high-quality and efficient refractory materials.

What are the Requirements for Refractory Materials in the Steel Smelting Process?

In the process of steel smelting, refractory materials should meet the following requirements.

①It has a wide operating temperature range, generally up to 1760℃.
②It can withstand rapid changes in temperature and has good thermal shock resistance. Prevent cracks and breaks in the refractory material of the furnace lining.
③Under high temperature and low-temperature conditions, it can withstand not too high compressive stress.
④It can withstand friction under high and low-temperature conditions.
⑤It has the ability to resist the corrosion of slag (including acid slag and alkaline slag).
⑥It can withstand the huge hydraulic pressure and buoyancy of molten metal.
⑦Can withstand the action of furnace gas, including CO, SO2, CO2, CH4, H2O, and volatile oxides and salts in metals. Prevent infiltration and effect on refractory materials.

Because the refractory has to withstand some of the above conditions, it usually acts as a high-efficiency isolation layer. Sometimes it needs to be a heat conductor or absorber, which is mainly determined by its application.　　

What are the Basic Performance Requirements of Refractory Materials for Steelmaking?

1) Refractories for converters

At present, magnesia-carbon bricks are used for the furnace cap, tapping opening, front and rear faces, molten pool, and furnace bottom of the converter. High-strength magnesia-carbon bricks are used for the trunnion and slag line. The content of MgO in the magnesia-carbon brick is generally 70-75%, the content of graphite is 16-20%, the bulk density is 2.8-2.9g/cm3, and the compressive strength is 25-30MPa. High-strength magnesia-carbon bricks have the same composition as magnesia-carbon bricks, but the compressive strength is 30-42MPa.

2) Refractories for electric furnaces

The furnace bottom, furnace slope, and molten pool of the electric furnace are integrally knotted with magnesia, or magnesia bricks combined with tar pitch are used. High-quality magnesia carbon bricks (https://rsrefractoryfirebrick.com/magnesia-carbon-bricks/) are used in hot spots and slag line areas. Both sides of the furnace door and the tapping port are made of magnesia bricks and chrome magnesia bricks. The electric furnace cover is made of high-alumina bricks or high-alumina non-burning bricks.

3) Refractories for ultra-high power electric furnaces

The permanent lining of the ultra-high-power electric furnace is magnesia refractory bricks. The side pillars of the furnace door are magnesia chrome bricks, and the slag line is magnesia bricks. The hot spot area is magnesia carbon bricks, the furnace wall is magnesia carbon bricks, and the eccentric bottom and molten pool are magnesia bricks. The tap hole is made of magnesia carbon brick, the electric furnace cover is made of high alumina brick, and the tap hole filler is made of high iron dolomite filler.

4) Refractories for open-hearth furnace

It can be seen from the working conditions of various steelmaking furnaces that the working environment of refractory materials is very harsh. Therefore, no matter what refractory material is used, it must have the following properties. (1) High-temperature resistance and high refractoriness. (2) Erosion and erosion of high-temperature molten steel and slag. (3) Steelmaking furnaces are intermittent operations, and refractories are required to have good thermal shock resistance and spalling resistance. (4) It has high mechanical strength and can withstand the impact of furnace body tilting and charging charge without damage.