Method of producing active lime in vertical kiln
Activated lime has important applications in many industrial fields, and vertical kilns are one of the commonly used equipment for producing activated lime. The following will provide a detailed introduction to the method of producing activated lime in a vertical kiln.
1、 Raw material preparation
Firstly, it is necessary to choose high-quality limestone as the raw material. High quality limestone should have a high content of calcium carbonate, usually above 95%, while minimizing impurities such as silicon dioxide, magnesium oxide, aluminum oxide, etc.
Crushing and sieving limestone to achieve the required particle size for vertical kiln production. Generally speaking, the particle size of limestone is more suitable between 40-100 millimeters. A particle size that is too small can easily lead to poor ventilation, while a particle size that is too large can affect the uniformity of calcination.
2、 Vertical kiln loading
The processed limestone is fed into the feeding port at the top of the vertical kiln through equipment such as elevators or conveyor belts. During the loading process, attention should be paid to the uniformity of the fabric to ensure the uniform distribution of air flow in the kiln and the uniform heating of limestone.
Different fabric methods can be used, such as rotating fabric cutters or multi-point fabric, to improve the effect of the fabric.
3、 Combustion control
The combustion system of a vertical kiln usually uses gas fuel (such as natural gas) or solid fuel (such as coal powder). The temperature and atmosphere of combustion have a significant impact on the activity of lime.
Control the combustion temperature between 1000-1200 degrees Celsius. Excessive temperature may lead to overburning of lime and reduce its activity; Too low a temperature will result in incomplete calcination and affect the quality of lime. At the same time, it is necessary to ensure the oxidizing atmosphere inside the kiln and avoid the occurrence of reducing atmosphere, so as not to affect the quality of lime.
4、 Ventilation management
Good ventilation is the key to ensuring the normal operation of vertical kilns and the production of high-quality activated lime. Inject an appropriate amount of air into the kiln through a fan, control the air volume and speed to promote fuel combustion and limestone decomposition.
The size of ventilation should be adjusted according to the temperature, pressure, and fuel combustion inside the kiln to ensure uniform gas flow and avoid local overheating or undercooling.
5、 Calcination time
The length of calcination time depends on factors such as the particle size of limestone, kiln temperature, and ventilation conditions. Generally speaking, the calcination time is around 8-12 hours.
During the calcination process, it is necessary to closely monitor the temperature and pressure changes inside the kiln, adjust the calcination time according to the actual situation, to ensure that the limestone is fully decomposed and produces highly active lime.
6、 Cooling discharge
After calcination, the lime needs to be cooled. Natural cooling or forced cooling can be used. The natural cooling time is relatively long, but it has little effect on the activity of lime; The forced cooling rate is fast, but attention should be paid to controlling the cooling rate to avoid cracking of lime due to excessive cooling.
The cooled lime is discharged through the discharge device at the bottom of the kiln, and then screened and packaged to obtain the final active lime product.
7、 Quality control
In order to ensure that the produced active lime meets quality requirements, strict quality testing is necessary. The testing items include the calcium oxide content, activity, impurity content, etc. of lime.
According to the test results, adjust the production process parameters in a timely manner, such as combustion temperature, ventilation rate, calcination time, etc., to ensure the stability of product quality.
For example, if the activity of lime is found to be insufficient during testing, it may be necessary to increase the calcination temperature or extend the calcination time appropriately.
The production of active lime in vertical kilns requires strict control over various aspects, including raw material preparation, loading, combustion, ventilation, calcination time, cooling, and quality control. Only by achieving precise management and optimized operations at every stage can high-quality activated lime be produced to meet the needs of industrial production.
