May 10 2002
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Monolithic refractories are used in numerous applications and industries. This article covers these applications and the types of refractories that are used in particular parts of the operation. But the type of refractory used and even the kind of materials utilized in a specific application will vary from one plant to another, and the information given below is provided only as a guide.
Ferrous Metallurgy
The outer middle section of modern blast furnaces is lined with gunned insulating castables. The uptakes sections of the top of the blast furnace is also lined with a gunned insulating material. The blow pipe section, which connects the tuyeres to the bustle main pipe, is lined with a dense castable.
Besides this, the dense castables are used to strengthen the middle section of the blast furnace linings. A high-temperature dense castable formulation is used to line the blast furnace trough where molten iron exits the furnace. A high-strength castable is used to line the covering area of the blast furnace trough.
An acid-resistant gunned material is used to insulate the blast furnace stove. This furnace stove heats the air that is blown into the furnace from the tuyeres and subsequently burns the coke. A gunned castable is also used to line the stack section.
A high alumina monolithic refractory is used around the torpedo ladle’s spout. Torpedo ladles are used for conveying molten iron from the iron-making area of the plant to the steel area. Monolithic refractories are often used when short-term repairs are made to the torpedo ladle.
In steel plants, monolithic refractories are utilized in sections of the linings of converters, teeming ladles, vacuum degassers, molten steel ladles, and tundishes. In tundishes, most of the refractory lining is produced from a dense castable coated with magnesia. The converter’s outer lining is lined with a gunned castable.
The injection lance, utilized to blow gas into the steel in the converter, is made from a dense castable. The flooring in molten steel ladles is cast from high-strength magnesia spinel castable materials.
Petrochemical Applications
In applications like petroleum refineries, refractories are mainly used, keeping in mind their insulating and abrasion-resistant properties.
Sections such as reactors and cyclone walls are lined with dense high alumina castables. Different areas of chemical plants such as high-pressure vessels and reactors are generally lined with high-grade alumina monolithic.
Cement Plant Applications
Monolithic refractories are used in portions of cement kilns, usually at the outlet, where wear rates are higher. In these areas, dense silicon carbide-based castables are often used. Dense castables are used to line the cyclones in the pre-heater section of cement plants, owing to their complex shape and the wear resistance needed.
The shell of the exhaust gas duct is created from both dense and insulating castable material. In the cooler areas of the plant, the ceiling is lined with monolithic refractories.
Incinerators
Incinerators used for disposing of municipal waste, largely depend on different monolithic linings. The entrance section of the primary combustion chamber is lined with an abrasion-resistant castable.
The main section is typically lined with a high alumina plastic gunned material, which is supported with an insulating castable. The ducting that joins the primary combustion chamber with the secondary combustion chamber is lined with a dense castable, and so is the secondary chamber. The ducting that links the dust collectors to the stack is produced from an acid-resistant castable.
Non-Ferrous Metallurgy
Monolithics are mostly used as repair materials and backing insulation in the majority of non-ferrous applications.
In the aluminum sector, melting furnaces are made completely from monolithic refractories. While the heating chamber is lined with high alumina castable, sections in direct contact with the metal are created from phosphate-bonded plastic refractory.