High-alumina bricks
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Product Introduction
High-alumina bricks are aluminium-silicon refractory products made of bauxite clinker with a certain amount of combined clay with an Al2O3 content greater than 48%. On the basis of clay bricks, the Al2O3/SiO2 ratio was changed and the Al2O3 content was increased, so the refractory and high-temperature mechanical strength were better than those of clay bricks. The chemical properties of high-alumina bricks tend to be neutral, so the corrosion resistance of acid and alkaline slag is stronger than that of clay bricks and silica bricks.
High-alumina bricks are aluminium-silicon refractory products made of bauxite clinker with a certain amount of combined clay with an Al2O3 content greater than 48%. The production process of high-alumina bricks is basically the same as that of high-quality multi-clinker clay bricks. The difference is that there is a grading and sorting process and a post-screening iron removal process before clinker crushing.
On the basis of clay bricks, the Al2O3/SiO2 ratio was changed and the Al2O3 content was increased, so the refractory and high-temperature mechanical strength were better than those of clay bricks. The chemical properties of high-alumina bricks tend to be neutral, so the corrosion resistance of acid and alkaline slag is stronger than that of clay bricks and silica bricks. Therefore, all kinds of thermal equipment that originally used silica bricks or clay bricks can be replaced with high-alumina bricks. Replacing clay and silica bricks with high-alumina bricks can improve the service life of thermal equipment. At present, it is mainly used for masonry blast furnaces, hot blast furnaces, electric furnace roofs, steel barrels, cement kilns, glass kilns and chemical industry kilns, in addition to being used as lattice bricks for open-hearth regenerators, plug heads for pouring systems, nozzle bricks, etc. However, the price of high-alumina bricks is higher than that of clay bricks, so where the use of clay bricks can meet the production requirements, there is no need to use high-alumina bricks.
The Chinese standard (GB/T2988-1987) divides high-alumina bricks into four grades according to physical and chemical indicators：LZ-80、 LZ-75、LZ-70、 LZ-65、 LZ-55 and LZ-48。
| Projects | Physical and chemical indicators | ||||||
| LZ-80 | LZ-75 | LZ-70 | LZ-65 | LZ-55 | LZ-48 | ||
| (Al₂O₃)/% | ≥ | 80 | 75 | 70 | 65 | 55 | 48 |
| Apparent porosity/% | ≤ | 21 | 24 | 24 | 24 | 22 | 22 |
| Compressive strength at room temperature /MPa | ≥ | 70 | 60 | 55 | 50 | 45 | 40 |
| 0.2 MPa The load softens at the beginning temperature/°C | ≥ | 1530 | 1520 | 1510 | 1500 | 1450 | 1420 |
| Heating permanent line changes/% | Xmin Xmax | 1500℃X2h -0.4～0.2 | 1450℃×2h -0.4～0.1 | ||||
Key words:
High-alumina bricks
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