Limestone is a versatile sedimentary rock with numerous industrial applications. The method of processing limestone depends on its intended use, but generally involves several key steps:
1. Quarrying (Extraction)
– Limestone is extracted from open-pit mines or underground quarries using drilling and blasting.
– Large blocks are cut using diamond wire saws or mechanical splitters.
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2. Crushing & Screening
– Primary crushing: Large rocks are reduced to smaller pieces (6–10 inches) using jaw or gyratory crushers.
– Secondary crushing: Further reduced to 1–3 inches using cone or impact crushers.
– Screening: Sized into different grades using vibrating screens.
3. Grinding (For Powdered Applications)
– Ball mills or vertical roller mills grind limestone into fine powder (for cement, agriculture, or industrial fillers).
– Raymond mills produce ultra-fine powders for applications like paint, plastics, and rubber.
4. Calcination (For Quicklime Production)
– Limestone (CaCO₃) is heated in a rotary kiln at 900–1200°C to produce quicklime (CaO) and CO₂ gas:
\[
\text{CaCO}_3 \xrightarrow{\text{Heat}} \text{CaO} + \text{CO}_2
\]
– Quicklime is then hydrated to produce slaked lime (Ca(OH)₂).
5. Hydration (For Slaked Lime)
– Quicklime reacts with water in a controlled process:
\[
\text{CaO} + \text{H}_2\text{O} → \text{Ca(OH)}_2 + \text{Heat}
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Used in water treatment, construction, and chemical industries.
6. Classification & Packaging
– Processed limestone is classified by size and purity.
– Packaged in bulk (silos, trucks) or bags for distribution.
Common Applications of Processed Limestone
| Product | Uses |
|——————|———|
| Crushed Stone | Construction, road base, concrete aggregate |
| Ground Limestone | Soil conditioner, animal feed additive |
| Quicklime (CaO) | Steelmaking, flue gas treatment |
| Slaked Lime (Ca(OH)₂)| Water treatment, mortar, paper production |
|