The Influence of Physical Properties of Lime Production Raw Materials on Production Process
The physical properties of lime production raw materials directly determine the setting of process parameters and equipment selection, and their impact runs through the entire process of crushing, calcination, and finished product quality. The specific manifestations are as follows:
1. Particle size distribution affects preprocessing energy consumption
If the raw limestone particles are too large (>100mm), the number of crushing stages needs to be increased, resulting in a 20% -30% increase in electricity consumption; If it is too thin (<30mm), it is easy to form a dense layer in the calcination zone, which hinders the penetration of hot gas. Optimization strategy: Adopting a graded crushing and screening system, controlling the particle size of 40-80mm when entering the kiln, while balancing crushing efficiency and breathability.
2. The moisture content determines the design of the preheating section
When the moisture content is greater than 3%, the moisture evaporates and absorbs heat after entering the kiln, causing a sudden drop in kiln head temperature of 80-120 ℃, and the preheating section length needs to be extended. Solution: Set up a raw material drying system (such as a rotary dryer) to reduce the moisture content to<1% and simultaneously recover waste gas and heat.
3. Impurity content restricts calcination temperature
When SiO ₂>2%, the melting temperature of impurities (1713 ℃) is higher than the decomposition temperature of CaCO ₂ (825 ℃), and it is easy to form molten silicate to encapsulate unreacted limestone. Therefore, the calcination temperature needs to be increased to above 1150 ℃. Response measures: Control SiO ₂<1.5% during raw material screening, or adopt segmented temperature control in double chamber kilns.
4. Porosity affects thermal conductivity efficiency
The thermal conductivity of dense limestone (porosity<5%) is only 1.8-2.5W/(m · K), and the calcination time needs to be extended by 30% -50%; Porous structures (porosity>15%) are prone to local overheating and increase kiln body corrosion. Process optimization: Inducing microcracks through pre calcination (700 ℃) to improve thermal conductivity efficiency.
5. Hardness related equipment loss
Raw materials with a Mohs hardness greater than 3.5 exacerbate the wear of the crusher hammer head, requiring the use of high manganese steel material and shortening the maintenance cycle. Raw materials with a hardness of less than 3 are prone to forming powder in the kiln, increasing the dust removal load. Equipment selection: When the hardness is greater than 4, choose a cone crusher, and when it is less than 3, give priority to using an impact crusher.
In actual production, it is necessary to establish a raw material database, analyze mineral composition through XRD, and dynamically adjust process parameters by combining online particle size detectors and moisture analyzers. For example, a certain enterprise adopts an intelligent batching system to automatically optimize the calcination curve based on the real-time properties of raw materials, resulting in a 5% increase in lime activity and a 12% reduction in energy consumption. This fully demonstrates that precise control of the physical properties of raw materials is the key to improving the quality and efficiency of lime production.
