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Guy Barnes
Asked a question 2 years ago

What are Refractory Bricks and mention it's types?

What are refractory bricks and mention it's types?

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A fire brick, firebrick, or refractory is a block of ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency.

There are mainly three varieties of refractory bricks;

a) Acid Refractories
i. Ordinary Fire Bricks
ii. Silica Bricks
iii. Ganister Bricks

b) Basic Refractories
i. Magnesite Bricks
ii. Dolomite Bricks
iii. Bauxite Bricks

c) Neutral Refractories
i. Chromite Bricks
ii. Carborundum
iii. Chrome Magnesite Bricks
iv. Spinal Bricks
v. Forsterite Bricks

Fire clay bricks or Refractory bricks

Fire bricks or fire clay bricks or refractory bricks are made from the fire clay. The process of manufacturing of these bricks is same as the ordinary bricks but are burnt at very high temperatures in a special type of kilns generally Hofmann’s kill. The raw materials of these bricks consists of flint clay and grog that has burned fire clay as non plastic materials and soft fire clay as plastic material.


  • Color of these bricks is whitish-yellow or light brown.
  • Comp strength of fire clay bricks varies from 3.5 N/mm2 to 48.26 N/mm2.
  • The water absorption % of fire bricks varies from 4 – 10%.
  • These bricks are generally used in lining furnaces kilns, fire boxes and fireplaces.

Principal types

Acid Refractory bricks

  • Silica bricks: 95 – 97% silica, 1 – 2% lime
  • Ganister bricks: 98% ganister a hard colored stone with 10% clay, 2% lime.

These are generally used in lining furnaces having siliceous & acidic slag steel industry and coke oven.

Basic Refractory bricks.

basic refractory bricks are manufactured from magnesia, dolomite, bauxite, etc.

  • Magnesia bricks: magnesium above 85%, calcium oxide up to 25% & silica up to 5.5%.
  • Bauxite bricks: aluminium oxide above 85% & clay up to 20 %.

these type of bricks are highly resistant to corrosion and are used for lining furnaces having basic slag.

Neutral Refractory Bricks

  • Chromite bricks: 50% chrome, 30% Iron oxide, 20% Bauxite.
  • Chrome magnesite bricks: A mixture of chrome ore and magnesite ore with a min % of Chromium (III) Oxide is >18% & Magnesium Oxide is >30%.
  • Spinel bricks: Made from the refractory slag produced in an electric furnace consisting of magnesia & alumina.
  • Forsterite bricks: Made from mineral forsterite

The neutral refractory bricks are used in places where acidic and basic linings are to be separated.

Terry Collins
Sustainability consultant
What are Refractory Bricks and mention it's types?

Refractory bricks (fire brick):

Let’s discuss the definition of refractory bricks first.

Definition :

Refractory brick is a block of ceramic material specially used in kilns, lining, furnaces, fireboxes and fireplaces.

A speciality of fire brick :

  • It can withstand very high temperature up to 1649 degree Celsius
  • It has low thermal conductivity for Greater Energy Efficiency

Chemical composition of refractory brick :

  • Silica (SiO2) :  60-96 percent
  • Alumina (Al2O3) : 2- 36 percent
  • Magnesia,iron oxide, lime, alkalis : 2 to 5%

The manufacturing process of fire brick :

  • Digging
  • Weathering
  • Tempering
  • Moulding
  • Burning

Types of Refractory Bricks :

A) Basic Refractory Bricks :

  1. Magnesite brick (85% magnesium oxide + 35 % iron oxide)
  2. Dolomite refractory brick ( it can resist at 1400 degree Celsius to 1600 degree celsius temperature)
  3. Bauxite refractory brick( 86 per cent bauxite)

B) Acid Refractory Bricks :

  1. Ordinary fire brick
  2. Silica Bauxite (95% silica)
  3. Ganister brick (85% silica + 10% clay + 2% lime)

C) Neutral Refractory Bricks :

  1. Chromium brick (50% Chrome iron ore)
  2. Carborundum (temperature of 21900 degree Celsius)
  3. Chrome magnesite brick
  4. Spinal brick (Alumina and magnesia has equal proportion)
  5. Forsterite Brick

Refractory brick is a brick that can stand against higher temperatures.

Basically, refractory brick is used in kilns, havan kund, furnace, chimney.

type of refractory brick

  • High alumina brick
  • Dolomite bricks
  • Fire clay brick
  • Magnetite brick

For more information

Refractory Bricks are ceramic material that normally used for high-temperature environments because of their decent insulator and flammability property.

They are used for the construction of kilns, furnaces, and other high temperature subjected structures.

Types of Refractory Bricks:-

  1. Chromite refractory brick
  2. Silica refractory brick
  3. Fire clay bricks
  4. High alumina refractory bricks
  5. Magnetite refractory brick
Henry Newman
Water resource engineer

A fire brick is a special type of brick made using fire clay and has a good resistance against high temperatures which are used in kilns, lining furnaces, fireplaces, and fireboxes. These bricks are manufactured in a way similar to that of normal bricks, except during the burning process- Fire bricks are exposed to very high temperatures.

To read more about properties, types, and uses of fire bricks, please visit the following link: