High Alumina Refractory Brick
Introduction:
High alumina refractory bricks are made from bauxite or kaolinitic clays. The definition high-alumina refractory bricks contain between 48 and 89 percent alumina. They are much harder and tougher than same grade of fireclay refractories at high temperatures and in basic environments. In addition, high alumina refractory bricks exhibit better volume stability and abrasion resistance. High alumina bricks are used in blast furnaces, blast-furnace stoves, and liquid-steel ladles etc.
The high alumina bricks are basically divided into three grades as per the amount Al2O3 they contain. These are
Grade I which includes Al2O3 for in the range of 75~81%
Grade II which includes Al2O3 for in the range of 60~75%
Grade III which includes Al2O3 for in the range of 48~60%
Top Grade which includes Al2O3 for in the range of 82~89%
Properties of High Alumina Bricks
The high alumina bricks are basically perfect and advanced refractory materials having a very high refractoriness up to 1750~1790, which is much higher than that of fire clay bricks and semi-silica bricks obviously.
The high alumina bricks are very durable in nature and are also well designed to be used in high-temperature area such as blast furnaces.
The high alumina bricks are usually constructed with higher refractoriness and low impurities.
These bricks include more Al2O3 content than that of other ones in the same category and hence can also be referred to neutral refractory material having resistance to acid and basic slag erosion.
Along with Al2O3 these bricks also comprise of SiO2 content which enhance the resistance to acid slag erosion much more..
Chemical Composition (wt%) | Apparent Porosity (%) | Bulk density (g/cc)Min. | CCS (kg/cm2) | PLC (%) | PCE (0C/OC) Min. | RUL (Ta0C) | Application Area | |
Al2O3 | Fe2O3 | |||||||
52-56 | 1.7-2.2 | 16-21 | 2.35 | 500-700 | -0.8 to 0.3 at 15000C/2h | 1763/34 | 1450-1500 | Reheating Furnace Roof & Petro-Chemicals. |
57-60 | 3.4-4.2 | 17-22 | 2.35 | 550-800 | -0.4 to 2.0 at 14500C/2h | 1785/35 | 1420-1450 | Reheating Furnace Wall, Burning Ladle Back up. |
61-64 | 1.2-1.5 | 13-16 | 2.42 | 600-900 | ±0.5 at 15000C/2h | 1804/36 | 1500-1550 | Blast Furnace Hearth, Non-Recovery Coke Oven, Glass Tank Furnace & Frit Furnace. |
68-72 | 1.4-1.8 | 16-21 | 2.52 | 600-900 | -0.2 to 2.0 at 15000C/2h | 1820/37 | 1500-1530 | Burning Zone of Cement Rotary Kiln, Lime Kiln & Steel Ladle. |
77-80 | 2.2-2.7 | 17-22 | 2.70 | 700-900 | -0.5 to 2.5 at 15500C/2h | 1820/37 | 1490-1520 | EAF Roof, Steel Rolling Mill, Steel Ladle & other high heat duty special applications. |
82-85 | 1.4-1.8 | 13-17 | 2.80 | 850-1200 | -0.3 to 1.0 at 15500C/2h | 1850/38 | 1540-1580 | Non-wetting Phosphate-bonded bricks for Aluminium Melting & Holding Furnace, Reheating Furnace Bottom etc. |
86-89 | 1.0-1.8 | 44911 | 2.85 | 900-1200 | -0.2 to 0.5 at 15000C/2h | 1820/37 | 1580-1620 | Reheating Furnace Bottom (specially Coal-fired). |
Characteristic as follows:
a, refractoriness; high alumina bricks refractoriness are higher than clay and semi-silica brick refractoriness up to 1750 ~ 1790℃, belonging to high-grade refractory.
b, load softening temperature; high aluminum products because of high Al2O3, less impurities, less fusible vitreous formed, so load softening temperature is higher than the clay brick, but not formed mullite crystalline , so load softening temperature silica brick is still not high.
c, slag resistance; Al2O3 in alumina bricks are more close to neutral refractories, resistant to erosion of acid and alkaline slag slag, because it contains SiO2, so resistance to alkaline slag ratio of acid slag ability weaker.
Application of High Alumina Refractory Bricks
The high alumina bricks are mainly used in masonry in blast furnace, hot blast furnace, electric furnace roof, blast furnace, reflecting furnace, lining of rotary kiln. In addition, high alumina brick are widely used in open hearth furnace lattice brick, plug used in casting system, nozzle brick, etc. But the price of high alumina brick is higher than the clay brick, so we do not need high alumina brick when the clay brick can satisfy the demand.
