The Ground Calcium Carbonate (GCC) process involves extracting, crushing, grinding, and classifying limestone or marble to produce fine or ultra-fine calcium carbonate powder. Here’s a step-by-step breakdown of the typical GCC production process:
1. Mining & Quarrying
– Limestone or marble is extracted from open-pit mines or quarries using drilling and blasting techniques.
– High-purity deposits (≥95% CaCO₃) are preferred for high-quality GCC.
2. Primary Crushing
– Large rocks are crushed into smaller pieces (typically <50 mm) using jaw crushers, impact crushers, or hammer crushers.
3. Washing & Beneficiation (Optional)
– Impurities like clay, silica, and iron are removed through:
– Wet scrubbing (for clay removal).
– Magnetic separation (for iron removal).
– Froth flotation (if high purity is required).
4. Grinding (Dry or Wet Process)
# (a) Dry Grinding Process
– Crushed limestone is dried and fed into a ball mill, vertical roller mill, or pendulum mill.
– Ground material is classified by an air classifier to separate fine particles (<10–45 µm).
– Coarse particles are recycled for further grinding.
# (b) Wet Grinding Process
– Used for ultra-fine GCC (<2 µm).
– Limestone is ground in a wet ball mill or attrition mill with water.
– A hydrocyclone or centrifuge separates fine slurry from coarse particles.
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5. Classification & Separation
– Air classifiers (dynamic or static) separate particles by size in dry processes.
– Hydrocyclones or centrifuges classify wet-ground slurry.
6. Surface Treatment (Optional)
– For specialty applications, GCC may be coated with:
– Stearic acid (for hydrophobic properties in plastics).
– Titanate/silane coupling agents (for improved polymer compatibility).
7. Drying (Wet Process Only)
– Filtered slurry is dried in a spray dryer, rotary dryer, or flash dryer to remove moisture.
8. Packaging & Storage
– Final GCC powder is packed in bags, bulk containers, or silos based on customer requirements.