Fire Clay Brick

Fire Clay Brick

Fire clay brick is a refractory brick made from a special type of clay that can withstand very high temperatures without melting or deforming. It is used in construction of kilns, furnaces and other industrial equipment that requires high temperature resistance. It is a very dense type of refractory brick that can withstand extreme mechanical, chemical and thermal stresses. It can also resist cracking and spalling caused by rapid changes of temperature.

There are various types of fire clay bricks available in the market which differs in their refractoriness, volume stability at different temperatures and their hot crushing strength. Normally, fire clay bricks are produced through dry-press, stiff-mud casting and soft-mud molding processes. These are then fired in a superior type of kiln under controlled conditions to achieve the desired properties and characteristics of refractory bricks.

The raw materials required for the production of fire clay bricks include flint and bond clays as well as kaolin. A portion of the raw material blend is usually precalcined to control drying and firing shrinkages and to impart refractoriness. Moreover, plastic clays which facilitate forming and provide bonding strength are added to the mix. The clays have high fusion and softening points to ensure that the bricks can be formed into required shapes.

When the refractory clay is mixed with other additives, it becomes hard enough to be pressed into molds and shaped to specific designs. Afterwards, it is dried for several days in tunnel or humidity driers. During this process, the moisture content in the bricks is driven off and organic substances such as iron oxides and sulphur compounds and organic matters are removed. At the same time, the mineral composition and volume of the bricks are stabilized.

Typically, super duty, high duty and medium duty fire clay bricks are the most common types of fire bricks in use today. These bricks are mainly used for building kilns and furnaces that require extreme chemical, physical and thermal stresses. They are capable of withstanding high refractory temperatures and have low thermal conductivity to maximize energy efficiency.

A typical fire clay brick contains 50-75% silica and 25-35% alumina and has a pH of less than 10. It can withstand extremely high temperatures and can be used in lining kilns that will experience frequent changes of temperature as well as abrasion from refractory linings and fluxing agents such as slag and sludge.

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