What are the uses of magnesia carbon bricks

High-temperature industries like steel, nonferrous metals, and cement all rely on refractory bricks. Magnesia-carbon bricks, due to their resistance to corrosion, high temperatures, and spalling, have become the standard for furnace linings. What are the uses of these bricks? This article provides a detailed introduction.

1.Steelmaking converter and electric furnace

(1)Application of converter

The converter’s hotspot temperature soars to 1700°C, and with the addition of high-oxygen blowing, ordinary refractory materials will melt in a few hours.

At this point, magnesia-carbon bricks stand out thanks to their composite structure of high-purity magnesia and carbon. They first protect against slag with a carbon layer, then against corrosion with magnesia. This alternating protection increases the life of the furnace lining from dozens of furnaces to over a hundred.

(2)Electric furnace related applications

The situation in electric furnaces is similar to that of converters. The slag line of the furnace wall is also subject to scrap impact and arc radiation. The carbon content in magnesia-carbon bricks is stabilized at 10% to 20%. This ensures electrical conductivity and heat dissipation while also inhibiting slag penetration. Therefore, magnesia-carbon bricks are almost exclusively used in the slag line and hotspot zones of large electric furnaces.

2.Ladle refining: magnesia carbon bricks are indispensable in the slag line area

During secondary refining in the ladle, the basicity of the top slag is as high as 3 to 4. At this time, fluoride ions are active and corrode refractory materials the fastest. The slag line is the first to be eroded. Therefore, without the use of magnesia-carbon bricks, the slag liquid will penetrate the working layer through the pores, causing “lap penetration” accidents.

Subsequently, refining stations such as the RH and LF require electrical heating, with arc spot temperatures exceeding 1800°C. However, the carbon mesh within the bricks quickly dissipates the heat, reducing local overheating. This, in turn, extends the life of the slag line.

In addition, the impact area of ​​the ladle wall is washed by the molten steel circulation, and this brick can also be used. It takes into account both toughness and corrosion resistance, so that the ladle will not be contaminated by molten steel during the entire refining cycle.

3.Nonferrous smelting and cement kiln

Although copper and nickel converter blowing temperatures are lower than steelmaking, the high viscosity of the Fe₃O₄ magnetic slag makes mechanical erosion more severe. In this case, the high-hardness carbon skeleton of the magnesia-carbon bricks first blocks the mechanical erosion, and then the magnesia particles react with the FeO in the slag to form high-melting-point minerals, which automatically repair the surface layer and extend the furnace life to more than six months.

Looking at the high-temperature zone of a cement rotary kiln, flame temperatures can reach 1800°C. Ordinary magnesia-chrome bricks are prone to ring formation and contain chromium, a hazard. Magnesia-carbon bricks, however, are different. Their carbon layer does not wet the clinker, reducing ring formation thickness and kiln load, potentially increasing clinker production by hundreds of tons per day.

In short, different industrial scenarios have different performance requirements for magnesia carbon bricks. Therefore, we should try our best to select materials scientifically, and at the same time, we should also pay attention to choosing refractory brick suppliers with technical strength and production experience.