Analysis Of The Dual Function And Industry Application Of Limestone In Cement Manufacturing

Core application areas

Limestone, as one of the most important industrial minerals, is consumed in the cement industry, accounting for over 70% of the global limestone consumption. In the new dry process cement production line, approximately 1.1-1.3 tons of limestone raw materials are consumed for every ton of cement clinker produced.

The two core roles in cement production

As the main raw material for cement clinker (accounting for 80-90%)

* Chemical Mechanism * :

A series of chemical reactions occur through high-temperature calcination:

Decomposition reaction: CaCO₃ → CaO + CO₂↑ (starting from 900℃)

- Mineral phase formation: 2CaO + SiO₂ → C₂S (1300℃)

3CaO + SiO₂ → C₃S (1450℃)

* Key Points of Process Control *

Composition requirements: CaO≥48%, MgO≤3%, SiO₂≤4%

- Particle size control: The sieve residue of raw material with a fineness of 80μm is ≤12%

- Homogenization degree: The CaO fluctuation of raw materials entering the kiln is ≤±0.2%

As a mineral admixture (accounting for 5-15%)

Cement production process flow (Key nodes of limestone treatment)

Raw material preparation stage

- Crushing system: Two stages and one closed-circuit process

- Primary crushing: Jaw crusher (feed ≤800mm, output ≤150mm)

- Secondary crushing: Impact crusher (output ≤30mm)

-Pre-homogenized storage yard: The Chevron stacking method is adopted, with a homogenization effect H≥8

Calcination and transformation stage

- Five-stage preheater system: Heat the material up to 800℃

- Rotary kiln section:

- Decomposition zone (900-1100℃) : Limestone is completely decomposed

- Firing zone (1450℃) : C₃S mineral formation

Finished product preparation stage

- Cement grinding: Closed-circuit ball mill system + high-efficiency classifier

- Blending process:

- Limestone powder fineness: specific surface area 400±20m²/kg

- Optimal dosage: Controlled in accordance with ASTM C595 standard