Typical Refractories in Industrial Use

Depending on the area of application such as boilers, furnaces, kilns, ovens etc, temperatures and atmospheres encountered different types of refractories are used. Typical installations of refractories are shown in Figure 5.6

Figure 5.6

Fireclay Refractories

Fireclay refractories, such as firebricks, siliceous fireclays and aluminous clay refractories consist of aluminium silicates with various amounts of silica ranging from SiO₂ content of less than 78% and containing less than 44% of Al₂O₃.

Table 5.6 shows that as the quantity of impurities increases and the amount of Al₂O₃

5. Insulation & Refractories

decreases, the melting point of fireclay brick decreases. Owing to its relative cheapness and widespread location of the raw materials used to manufacture firebricks, this material finds use in most furnaces, kilns, stoves, etc.

Firebrick is the most common form of refractory material. It is used extensively in the iron and steel industry, nonferrous metallurgy, glass industry, pottery kilns, cement industry, and by many others.

TABLE 5.6 PROPERTIES OF TYPICAL FIRECLAY BRICKS
Brick	Percent SiO2	Percent Al2O3	Other Constituents	PCE °C
Super Duty	49-53	40−44	5-7	1745-1760
High Duty	50-80	35-40	5-9	1690-1745
Intermediate	60-70	26-36	5-9	1640-1680
HighDuty (Siliceous)	65-80	18-30	3-8	1620-1680
Low Duty	60-70	23-33	6-10	1520-1595