Processing calcium carbonate powder from raw materials involves several steps to achieve the desired purity, particle size, and properties. Below is an outline of a typical calcium carbonate (CaCO₃) powder processing plant:
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1. Raw Material Preparation
– Source Selection: Calcium carbonate can be sourced from:
– Limestone (Natural CaCO₃): Mined from quarries.
– Marble or Chalk: High-purity alternatives.
– Precipitated Calcium Carbonate (PCC): Chemically synthesized (e.g., via carbonation of lime).
– Crushing: Large rocks are crushed into smaller pieces using jaw crushers or hammer mills.
– Washing: Impurities like clay or silt are removed by washing.
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2. Grinding & Milling
– Coarse Grinding: Initial grinding with a hammer mill or impact crusher to reduce particle size.
– Fine Grinding:
– Ball Mill / Raymond Mill: For medium-fine powder (45–150 µm).
– Ultrafine Grinding (for high-value products):
– Vertical Roller Mill (for 10–45 µm).
– Jet Mill / Classifier Mill (for <10 µm, D97).
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3. Classification & Separation
– Air Classifiers: Separate particles by size (e.g., for GCC – Ground Calcium Carbonate).
– Screening/Vibrating Sieves: For coarse particle removal.
– Magnetic Separators: Remove iron impurities.
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4. Surface Treatment (Optional)
For specialty applications, CaCO₃ may be coated with:
– Stearic acid or silane for improved polymer compatibility.
– Titanate coupling agents for enhanced dispersion.
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5. Drying & Packaging
– Rotary Dryer / Flash Dryer: Reduces moisture content (<0.5%).
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ing: Bagged in 25–50 kg sacks, bulk bags, or silos for industrial buyers.
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6. Quality Control & Testing
– Particle size distribution (laser diffraction).
– Brightness/whiteness (ISO 2470).
– Chemical purity (XRF or titration methods).
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Applications of Processed Calcium Carbonate Powder
| Industry | Use Case |
|———-|———|
| Plastics | Filler in PVC, HDPE |
| Paper | Coating &