Ceramsite, because of its excellent heat insulation, sound insulation, anti-corrosion, small specific gravity and other characteristics, is widely used in wallboards, blocks, lightweight concrete and other directions, playing a major role in replacing sand and gravel aggregates and reducing building costs heavy effect.
The traditional expanded ceramsite is directly granulated and fired with clay. With the development of society, this extensive and purely resource-consuming ceramsite production method has been gradually banned and replaced. The current development direction is mainly concentrated in various solid wastes co-processing to produce ceramsite.
However, not all building materials can be fired into ceramsite.
To judge whether one or several materials can be mixed into ceramsite, it mainly depends on the proportion of several inorganic oxides that can form glass phase in the raw materials: aluminum oxide, silicon dioxide, iron oxide, calcium oxide, Magnesium oxide, sodium oxide, potassium oxide. These oxides play different roles when ceramsite is fired.
Aluminium oxide: fired to a certain temperature to form a glass phase, after cooling down, if the content of aluminum oxide is too high, the melting temperature of the material will be too high, and if the content is too low, the strength of the glass phase will be insufficient, and the bubbles will grains are broken, causing the ceramsite to not form. Its ideal composition is about 18%;
Silica: The main strength material, affects the temperature of ceramsite swell. If the content is too high, the strength of the glass phase will be too high, the swelling temperature will be too high, and the expansion effect will be poor. If the content is too low, the ceramsite will not be formed. Its ideal composition is about 55%;
Iron oxide: the main foaming material, it starts to react at about 600 ℃, and reacts with the reducing substances in the material to generate carbon dioxide, which is mostly used as a foaming agent in the raw material. If the content is too low, there will be fewer bubbles, and the fired ceramsite will have a larger volume than expanded ceramsite. If the content is too high, the glass phase on the surface of the molten ceramsite will be broken and the ceramsite will not be formed. Its ideal composition should be around 7%;
Calcium oxide + magnesium oxide: It mainly adjusts the melting temperature of ceramsite. When the content of these two increases, the melting temperature of the material will decrease. However, if these two components are too high, they will react with heavy metal ions in the ceramsite to form soluble heavy metal water-soluble salts, resulting in unqualified heavy metal leaching rate of the ceramsite. Its ideal composition is about 5%.
Potassium oxide + sodium oxide: Its main effect is similar to calcium oxide and magnesium oxide, but the effect is stronger.
If the material composition meets the above component content, it can theoretically be used as the raw material of expanded ceramsite, but the production of ceramsite not only depends on the raw material, but also depends on the process and equipment. The production of ceramsite mostly adopts plug-in rotary kiln, and the drying kiln in the first half is usually longer than the calcining kiln in the second half. The drying process should be slower to prevent the rapid evaporation of water in the ceramsite raw meal and cause the raw meal to burst. When calcining, the temperature should be raised quickly, so that when the ceramsite enters the molten state, the foaming components inside are still reacting, and the generated gas is fixed in the interior to achieve a better foaming effect.
The production of ceramsite requires not only the selection of raw materials, but also the selection of qualified equipment manufacturers and manufacturers with strong technical capabilities.
