Clay brick is a refractory material with an Al2O content of 30% to 48%, made of clay clinker as aggregate and refractory clay (soft clay or semi-soft clay) as binder. It is a refractory product with a wide range of uses and the largest output.
The production process of high alumina brick products is similar to that of multi-clinker clay products. The production process should be determined according to the specific conditions of actual production, raw material characteristics, product requirements and production conditions. Strict classification of clinker blocks before crushing, graded storage and iron removal of granular materials, and fine grinding of clinker and combined clay are adopted.
Clay Brick
The properties of clay products fluctuate over a wide range due to differences in the chemical composition of the products and the production process. Clay products generally have the following properties:
(1) Chemical and mineral composition. The Al2O3 content is 30% ~ 48%, the SiO2 content is 50% ~ 65%, and a small amount of alkali metal and alkaline earth metal oxides TiO2, Fe2O3, etc. The mineral composition is generally: mullite, cristobalite, quartz, and glass phases.
(2) The refractory degree is generally 1580~1750C, which increases with the increase of Al2O3/SiO2. When the content of low-melting impurities is high, the refractory degree of the product is significantly reduced.
(3) The load softening temperature is about 1250~1450C, and its variation range is wide. The starting deformation temperature is low, which is about 200~250C different from the 40% deformation temperature.
(4) The coefficient of linear expansion is low, and its thermal conductivity is also low.
(5) Thermal shock resistance is good and the fluctuation range is large. 1100C water cooling cycle is generally more than 10 times. This is related to the low linear expansion coefficient of clay products, the insignificant crystal transformation effect and the plasticity at high temperatures.
(6) Chemical erosion resistance: Because it is weakly acidic, it has strong resistance to acidic slag erosion and weak resistance to alkaline material erosion.
Clay products are acidic refractory products, and their acidity increases as the SiO2 content increases. It has certain corrosion resistance to acidic slag, but has poor resistance to alkaline slag corrosion. Therefore, clay products should be used as the lining of acidic kilns. It is also used in high-temperature kilns such as blast furnaces, hot blast furnaces, glass kilns, and carbon roasting furnaces.
High Alumina Bricks
The characteristics of high alumina bricks and high alumina products are as follows:
1.Load softening temperature. The load softening temperature of ordinary high-aluminum refractory products is generally above 1420~1550C, which is higher than that of clay refractory products, and increases with the increase in Al2O3 content. When Al2O3<70%, its load softening temperature increases with the increase in the ratio of mullite phase to glass phase. The quantity and nature of the liquid phase have a significant impact on the load softening temperature, thus reducing the impurity content in the raw material. It is beneficial to improve the load softening temperature and high temperature creep property; when Al2O3>70%, as the Al2O3 content increases, the load softening temperature does not increase significantly.
(2) Thermal shock resistance. The thermal shock resistance of ordinary high-alumina refractory products mainly depends on the chemical mineral composition and microstructure. It is generally worse than clay products.
(3) Chemical erosion resistance. Ordinary high-alumina refractory products have good resistance to erosion and oxidation and reduction reactions by acidic or alkaline slag and molten metal, and the resistance increases with the increase of Al2O3 content and the decrease of harmful impurity content.
High-alumina products are generally used in industrial furnaces such as blast furnaces, hot blast furnaces, and electric furnaces.
2.The physical and chemical indicators of high alumina bricks are divided into several brands: LZ-80, LZ-75, LZ-65, LZ-55, LZ-48.
|
Brand/Item |
Fire clay |
High-Alumina |
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|
N-1 |
N-2a |
N3 |
N-4 |
LZ-85 |
LZ-80 |
LZ-75 |
LZ-65 |
LZ-55 |
LZ-48 |
|
|
Al2O3 % |
≥42 |
≥40 |
≥40 |
≥85 |
≥80 |
≥75 |
≥65 |
≥55 |
≥48 |
|
|
Refractoriness ℃ |
≥1750 |
≥1730 |
≥1690 |
≥1700 |
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|
Softening temperature under load ℃ |
≥1400 |
≥1350 |
T2≥1450 |
≥1300 |
≥1550 |
≥1530 |
≥1520 |
≥1500 |
≥1470 |
≥1450 |
|
Reburning line change rate % |
1400℃×2h +0.1～-0.4 |
1400℃×2h +0.1～-0.5 |
1350℃×3h +0.1～-0.5 |
1350℃×2h +0.2～-0.5 |
1500℃×2h +0.1～-0.4 |
1500℃×2h +0.1～-0.4 |
1500℃×2h +0.1～-0.4 |
1500℃×2h +0.1～-0.4 |
1450℃×2h +0.1～-0.4 |
1450℃×2h +0.1～-0.4 |
|
Apparent porosity % |
≤22 |
≤24 |
≤24 |
≤24 |
≤23 |
≤22 |
≤23 |
≤23 |
≤22 |
≤22 |
|
Normal temperature compressive strength MPa |
≥29.4 |
≥24.5 |
≥25 |
≥20.0 |
≥55 |
≥55 |
≥50 |
≥45 |
≥40 |
≥35 |
|
Application |
All kinds of industry furnace and thermal equipment |
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