Grade-2 high alumina brick (LZ-65)

Secondary High Alumina Brick (LZ-65)

The secondary high alumina brick, designated as LZ-65, complies with the national standard GB/T 2988-2012, which is the official Chinese standard for high alumina bricks. The LZ-65 grade refers to secondary high alumina bricks with an Al₂O₃ content ranging from 60% to 75%. This standard defines key specifications including production dimensions and the physical and chemical properties of the bricks.

The manufacturing process of LZ-65 high alumina bricks is similar to that of multi-clinker fireclay bricks, but with a significantly higher proportion of clinker—up to 90–95% in the mix. Before crushing, the clinker must be sorted, graded, and de-ironed. These bricks are typically fired at higher temperatures, generally around 1500–1600°C in tunnel kilns, especially for Grade I and II high alumina bricks.

LZ-65 is a neutral refractory material with an alumina content exceeding 48%. It is made by shaping and calcining bauxite or other raw materials with high alumina content. It features excellent thermal stability, a refractoriness above 1770°C, and good slag resistance.

These bricks are commonly used as lining materials in steelmaking electric furnaces, glass melting furnaces, and rotary kilns for cement production.