Varieties of refractory Bricks

Varieties of refractory Bricks

There are mainly three varieties of refractory bricks, namely: 1.Acid refractories; 2.Basic refractories; and 3.Neutral refractories.

(1) Acid Refractories: Following are the different types of acid refractories:

(a) Ordinary fine bricks: These are made of ordinary natural fire clay with a mixture of crushed flin clay and sand. They provide very good type of acid refractory lining to furnaces. They can resist a high temperature of 1600

(b) Silica bricks: They contain 95% of silica and are manufactured from sandstones or quartzite with an addition of 2 to 3% of lime to act as a binding material and flux. Silica bricks are quite suitable for acid lining of furnaces such as manufacture of glass and also for the walls and arches of basic openhearth steel furnaces. They can resist a high temperature of 2000

(C) Ganister Bricks: They manufactured from the silicious variety of ganister rock containing 85% of silica and 10% clay with an addition of 2% of lime. They are very hard, compact and rigid at a high temperature of 2100.

(2) Basic Refractories: The following  are the different varieties of basic refractory bricks.

(a) Magnesia Bricks: They are manufactured from fire clay containing 85% of magnesium oxide, 3 to 5% iron oxide and the balance lime and alumina. The can resist a higher temperature of 1800 to  2100. They are used for basic lining of furnaces.

(b) Dolomite Bricks : They are manufactured from fire clay containing higher percentage of dolomite . They are cheep substitutes for magnesia bricks in furnace lining. They are weaker refractories but can be made stronger by the used of serpentine. They can resist a temperature of 1400 to 1600

(c) Bauxite Bricks : They are manufactured from fire clay containing 86% of bauxite. They can resist a higher temperature of 1600 C.

(3) Neutral Refractories :They are used for separating the acid and basic lining of furnaces to prevent them reacting together. The following are different varieties:

(a) Chromite Bricks : They are made from fire clay containing 50% of chrome iron , 30% iron oxide and 20% bauxite with little silica. They can resist a higher temperature 2000.

(b) Carborundum : This is a special type of natural refractory bricks. It is made from fire clay  containing higher percentage of silicon carbide. It is used in electric furnace. It can resist a high temperature 2000