With the gradual development of new dry-process cement equipment towards large-scale, the improvement of production capacity and fuel combustion efficiency has greatly increased the temperature of the entire rotary kiln system. Due to the increase in temperature, the conventionally configured ordinary alkali-resistant bricks can no longer meet the requirements of refractory materials for low-temperature work. Therefore, it is urgent to find a low-cost, high-performance refractory brick to replace silica mullite bricks.
01 Application of ordinary silica mullite bricks
At present, the refractory materials of the preheating decomposition zone of the new dry-process cement rotary kiln are mainly configured with silica-molybdenum bricks. Although they can meet production needs, the alkali content of the preheating decomposition zone of the cement rotary kiln is high, and the alumina content in silica-molybdenum bricks is high, and the ability to resist alkali erosion is insufficient, and alkali cracking is prone to occur, which affects the service life. In addition, silica-molybdenum bricks all use first-grade or special-grade alumina, and add 10%~25% SiC. The production cost is high, and its high thermal conductivity increases the fuel consumption of cement kilns, resulting in energy waste. Therefore, whether from the perspective of reducing cement clinker energy consumption or saving refractory resources, it is urgent to use resource substitution technology to develop a new type of aluminum-silica alkali-resistant brick with excellent alkali corrosion resistance and high temperature resistance for use in cement rotary kiln preheating decomposition zone to replace silica-mullite brick.
02 Low aluminum mullite bricks for cement kilns prepared from waste electric porcelain
Low-aluminum mullite bricks for cement kilns prepared from waste electric porcelain use low-aluminum mullite and high-pressure waste electric porcelain as the main raw materials, add quartz sand powder and other additives, use pulp waste liquid as a binder, and prepare a mixture through reasonable particle grading. After high-pressure molding and drying, low-aluminum mullite bricks are prepared by firing at 1 400°C. The performance of the developed new low-aluminum mullite bricks was compared with the current ordinary silica-mullite bricks, and the effect of the amount of high-voltage electric porcelain added on the performance of the fired samples was analyzed. The results show that low-aluminum mullite bricks have low thermal conductivity and alkali resistance, and are more suitable for the preheating decomposition zone of cement rotary kiln; at the same time, the product uses waste high-voltage electric porcelain as the main raw material, which also has practical significance for the rational use of resources.
03 Product advantages of low aluminum mullite bricks for cement kilns prepared from waste electric porcelain
1. Low raw material cost. Industrial waste electric porcelain, as the main raw material, has long been treated as industrial waste. With the development of the ceramic industry, the number of waste electric porcelain is increasing. How to reasonably develop and utilize these waste high-voltage electric porcelain has great practical significance.
2. Compared with ordinary silica-mullite bricks, low-aluminum alkali-resistant mullite bricks have low volume density and are 15% lighter than the same number of silica-mullite bricks. They can greatly reduce the load of the kiln and realize the lightweight kiln.
3. Low-aluminum alkali-resistant mullite bricks have low thermal conductivity, which can reduce the heat dissipation loss of the cylinder and play a role in energy saving and consumption reduction.
4. Low-aluminum alkali-resistant mullite bricks have excellent alkali resistance, and their thermal shock stability and load softening temperature meet the requirements for the use of cement kiln preheating decomposition zone. Therefore, they can completely replace silica-mullite bricks and be used in cement kiln preheating decomposition zone.
Low aluminum mullite bricks made of low-aluminum mullite and high-pressure waste electrical porcelain as the main raw materials have good alkali resistance, low thermal conductivity and volume density, and good thermal shock resistance. They can completely replace ordinary silica-mullite bricks and be used in the thermal decomposition zone of cement kiln top, reducing the load of cement kiln body, realizing the lightweight of kiln, and having good energy-saving and consumption-reducing effects. At the same time, the use of waste electrical porcelain promotes the rational use of resources and achieves the purpose of energy saving and environmental protection.
