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.
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.