Refractory Bricks | Bricks | Construction Materials | By Ashutosh Nautiyal

Refractory Bricks 

Refractory Bricks

Introduction to Refractory Bricks:-

• Refractory bricks or Fire bricks are made from fire-clay.

• Fire brick or Refractory brick was first invented in 1822 by William Weston Young.

• This brick is burnt at very high temperatures in Hoffman's kiln during its manufacturing.

• It is built primarily to withstand high temperature.

• These bricks have an aluminium oxide content that can be as high as 50-80%.

• They can sustain excessive heat without melting or fusion.

• The raw materials used for the manufacture of fire bricks consist of flint clay and burnt fire clay as non-plastic materials and soft fire clay as plastic material.

• They usually have a low thermal conductivity for greater energy efficiency.

• The two standard sizes of this brick are 229 mm * 114 mm * 76 mm and 229 mm * 114 mm * 64 mm.

Properties Of Refractory Bricks:-

• Their colour is whitish-yellow or light brown.

• Their water absorption varies from 4 to 10%.

• Minimum average compressive strength for them should be 3.5 N/mm².    

Uses Of Refractory Bricks:-

• They are used for lining blast furnaces, ovens, kilns, boilers and chimneys.

Types Of Refractory Bricks:-

Acid Refractory Bricks:-

• These bricks consist of silica bricks(containing 95-97% silica and 1-2% lime) and ganister bricks.

• The softening temperature for them bricks ranges from 1700 to 1800°C.

• They are used in lining furnaces having siliceous and acidic slag, steel industry and coke oven.

• They cannot be used for the lining of furnaces which have to be cooled and reheated frequently because of their tendency to spall during rapid temperature changes.

Basic Refractory Bricks:-

• These bricks consist of magnesia bricks(containing minimum 85% magnesia, maximum 25% calcium oxide and maximum 5.5% silica) and bauxite bricks(containing minimum 85% aluminium oxide and maximum 20% clay). 

• They are highly resistant to corrosion and are used for lining furnaces having basic slag.

• Their use is restricted to copper metallurgy and basic open earth due to their high thermal expansion and consequent poor resistance to spalling.

Neutral Refractory Bricks:-

• These bricks consist of chromite bricks(containing 50% chrome and iron ore, 30% iron oxide and bauxite, 15% aluminium and 5% silica), chrome magnesite bricks(containing 18% Cr₂O₃ and 30% MgO), spinel and forsterite bricks.

• They are suitable at places where acidic and basic linings are to be separated such as a copper reverberatory furnace.

*Self Typed

*Source- Internet, Books and Self-Analysis