Main properties and uses of magnesia-carbon bricks

Magnesia-carbon bricks are made from magnesia, deburned magnesia, fused magnesia, high-purity magnesia, and additives such as high-quality graphite and bauxite. The price and performance of magnesia-carbon bricks are greatly influenced by their graphite content. As the graphite content increases, the brick's strength decreases, its thermal expansion rate decreases, and its residual expansion rate increases.

Therefore, the graphite content in the bricks should be controlled to around 20%. Magnesia-carbon bricks have low slag wettability and excellent resistance to spalling and erosion, making them suitable for the slag line area of steel ladles, especially in multi-furnace continuous casting applications. To meet the needs of producing clean steel, the application of magnesia-carbon bricks in ladle refining has expanded from the slag line area to the sidewalls.

When laying magnesia-carbon bricks on steel ladles, care should be taken to avoid mixing them with bricks containing high SiO2 content. Otherwise, it will increase the local melting loss of magnesia-carbon bricks, and the melting loss mechanism is as follows:

Mainly used in the furnace lining and tapping port of steelmaking oxidation converters, hot spots in the furnace walls of high-power electric arc furnaces, as well as the lining of external refining furnaces and the slag line area of steel ladles, etc. During the smelting process, the usage conditions and damage conditions of different parts of the converter vary. To achieve balanced corrosion, the grade and quality of magnesia-carbon bricks selected for different parts of the converter under different usage conditions are also different.

The furnace mouth and cap areas experience extreme temperature fluctuations and severe slag erosion. Magnesium carbon bricks with excellent thermal shock resistance and strong slag resistance should be selected. The sides of the trunnion, besides being damaged during blowing, lack protective slag layer plates on their surfaces, making them difficult to repair and prone to carbon oxidation within the bricks. High-quality magnesia-carbon bricks with excellent slag resistance and oxidation resistance should be used. The slag line area is in prolonged contact with molten slag, suffering severe slag erosion. Magnesia-carbon bricks with superior slag resistance must be used. During oxygen blowing on the charging side, splashes of slag and molten steel can cause chemical corrosion, wear, and erosion. Additionally, direct impact and erosion from charging scrap steel and molten iron occur. Select magnesia-carbon bricks with strong slag resistance, high-temperature strength, and excellent thermal shock resistance. The furnace hearth and bottom experience relatively lighter erosion compared to other areas and can use standard magnesia-carbon bricks. However, damage is more severe when employing top-bottom composite blowing technology, especially during bottom blowing of gases like CO₂ and O₂. High-grade magnesia-carbon bricks with superior oxidation resistance, thermal shock resistance, high-temperature strength, and slag resistance should be selected. Selecting converter magnesia-carbon bricks with corresponding properties for different converter sections is an effective method to enhance the converter's technical and economic performance.

The raw material for preparing magnesia-carbon bricks is fused magnesia with 98% MgO content. These bricks feature low porosity, resistance to slag erosion, thermal shock resistance, and high-temperature strength. They are primarily used in basic oxygen furnaces, medium-grade magnesia, ladle slag lines, and electric arc furnace hot spots. Magnesia-carbon bricks are a high-quality refractory material. Their primary constituents are magnesium oxide and carbon, with MgO content ranging from 60-90% and carbon content from 10-40%. This material is formed by high-temperature baking of high-purity MgO particles, carbon materials, tar, asphalt, or resin. These magnesia refractory bricks exhibit properties such as slag corrosion resistance, thermal shock resistance, and thermal conductivity.

Magnesium carbon bricks are an unfired carbon composite refractory material. They are made from high-melting-point (2800°C) basic oxide magnesium oxide and high-melting-point carbon materials. This material is resistant to slag erosion and incorporates various non-oxide additives and carbon binders.

The magnesium oxide content in magnesia-carbon bricks is determined by the raw materials used. Common magnesia-carbon bricks primarily contain 72%, 74%, 76%, 80%, 82%, or 85% magnesium oxide. Steel Ladle Magnesium Carbon Bricks. The primary raw materials for producing magnesium carbon bricks include fused magnesia, graphite, metallic aluminum powder, metallic silicon powder (click link for product details), and liquid phenolic resin. These materials are mixed in a sand mixer and then pressed into shape using a press. Magnesium carbon bricks are applied to the slag line of ladles during steel refining and are also used in the lining sections of AC electric arc furnaces, DC electric arc furnaces, and converters.

Electric furnace magnesium-carbon brick steelmaking utilizes the heat generated by the arc between graphite electrodes as the heat source. Equipment includes DC electric furnaces and AC electric furnaces, with AC furnaces being predominant. Based on the damage mechanisms of electric furnaces, this work has developed and produced magnesium-carbon bricks tailored to electric furnace requirements.

Magnesium Carbon Brick