Refractory materials are a protective layer installed inside the furnace or kiln to insulate the steel structure from high temperatures. The layer also protects the structure from abrasion wears thermal shocks and chemical attack. This protective layer can contain various refractory materials such monolithic refractories like castable and gunning mixes or refractory bricks. The selection of these materials depends upon the temperature inside the structure and the chemical nature of the material being processed inside. When it comes to thickness of the layer, the lining thickness is generally around 80 - 300mm.
There are different types of refractory materials used to create a refractory lining. However, the selection of materials will depend on several factors. So to help you with the selection process, here is the proper selection method of refractory lining for different parts of the blast furnace.
Furnace Throat - This part is mainly for the charge of impact and wear. So the general lining material for this part can be steel or water cooled steel bricks.
Upper Part of the Furnace - It’s the part of the structure that is prone to carbon deposition reaction area, and alkaline metals. Zinc vapor erosion is also occurring in this region along with falling charge and rising gas flow erosion as well as wear and tear. The most suitable refractory material in this area is high-density clay bricks, high-density third-class high-alumina bricks or phosphoric acid-impregnated clay bricks.
Furnace Waist - This area of the furnace is frequently exposed to thermal shocks, alkaline metal, zinc and carbon analysis, initial chemical erosion of slag and high-temperature gas scour. The best material to use for refractory lining in this area is brick. Or you can also use silicon carbide brick or aluminum carbon brick.
Furnace Belly - Mostly damaged by scouring of high-temperature gas and the scouring of slag iron. Due to the very strong heat flux in this area, the best material you use is high alumina brick or aluminum carbon brick.
Hearth Tuyere Area - It’s the only area of the furnace where oxidation reaction happens, leading to high temperatures ranging from 1900 - 2400. So brick lining can be good for this part. In some modern blast furnace, the refractory materials can be made from high alumina, corundum mullite, corundum and silicon nitride-silicon carbide.
Heath Bottom and Bottom - In this area, you have to use a material that has high erosion resistance. Maybe you can use bricks, high-quality corundum, gray corundum bricks and carbonaceous microporous and hot pressed bricks.