Refractory bricks are widely used in various industrial sectors and high-temperature technology fields, and are indispensable production materials for cement enterprises in the process of clinker calcination. Alkaline and silica-alumina refractory bricks are used in cement enterprises. Previously, magnesium chrome bricks were the most widely used in rotary kiln firing belts. However, due to the pollution hazard of water-soluble hexavalent chromium, some industrialized countries (such as Germany, the United States, etc.) have passed legislation to limit magnesium the use of chrome bricks due to environmental awareness. China also has corresponding regulations on this. At present, the chrome-free refractory material has been fully implemented in the cement industry, and both the magnesia-iron brick and the magnesia-calcium brick in the firing zone can replace the original magnesia-chrome brick.

The different requirements of the clinker calcination and cooling system of the cement enterprise have different performance requirements for the refractory bricks, and the types of refractory bricks used are also different. The refractory bricks commonly used in cement enterprises are: high alumina bricks, dolomite bricks, magnesia chrome bricks, spinel bricks, anti-stripping bricks, silicon mullite bricks, etc.

High-aluminum bricks are mainly used in preheaters, decomposing furnaces, tertiary air ducts, decomposing belts for rotary kiln, and linings for grate coolers.

Dolomite bricks are often used in high temperature sintering of rotary kiln. Due to the inherent hydration of dolomite, it will absorb moisture and hydrate during the kiln shutdown, causing the brick to crack and peel off. Therefore, the dolomite brick is suitable for use in the rotary kiln with long operation period. Used in the rotary kiln calcining belt, the service life is longer than the original magnesia chrome brick.

The magnesia-chrome bricks that appeared in the 1950s have greatly improved the life of the lining. Magnesia-chrome bricks have always been dominant in cement rotary kiln refractories. In the 1960s, the emergence of large cement rotary kiln made magnesium oxide spinel bricks replace the position of magnesia chrome bricks in the transition zone. In order to reduce the environmental pollution of hexavalent chromium, low-chromium magnesia-chrome bricks and chromium-free alkaline refractories have been manufactured to replace magnesia-chrome bricks. Magnesia-chrome bricks are a very cost-effective refractory material if environmental pollution is not considered. At present, the cement industry has replaced the original magnesia-chrome bricks with magnesia-iron bricks and magnesia-calcium bricks in the firing zone, and implemented chromium-free refractory materials.

The magnesium-aluminum spinel brick has no chromium component and is an environmentally friendly product. It is mostly used in the front and rear transition zones of rotary kiln.

Magnesium iron spinel brick contains no chromium and is suitable for the entire alkaline zone of the rotary kiln (sintering zone, transition zone), and has excellent kiln skinning ability.

The anti-flaking brick is a zirconium-containing high-alumina brick, which belongs to an acid brick and is an ideal material for the transition zone and decomposition zone of the rotary kiln of cement enterprises. It can also be used in the kiln door cover, cooling machine and other parts of the rotary kiln.

Silicon mullite brick is essentially a high alumina brick with silicon carbide added. Suitable for the upper and lower transition zones of the rotary kiln and the pre-tropic zone. Many companies have proved that silicon-red brick or silica mullite brick can be used for the transition zone on the 5 000t/d precalciner to obtain a service life of more than 12 months.