A ball mill is a type of grinder used to grind and blend materials, including calcium carbonate (CaCO₃) for chalk production. Here’s a breakdown of its use for chalk manufacturing:
1. Purpose in Chalk Production
– Grinding: Reduces calcium carbonate (limestone, marble, or precipitated CaCO₃) into fine powder.
– Mixing: Ensures uniform blending with binders (likypsum or polymers) and pigments (for colored chalk).
2. Key Components of a Ball Mill
– Rotating Drum: Contains grinding media (steel or ceramic balls).
– Grinding Balls: Crush and grind the raw material into fine powder.
– Drive System: Motor and gearbox for rotation.
– Lining: Protects the drum from wear.
3. Process Parameters
– Speed: Optimal rotation speed (typically 65–75% of critical speed).
– Ball Size & Load: Varies based on desired fineness (e.g., 5–20 mm balls).
– Material Feed Size: Pre-crushed to <10 mm for efficiency.
– Grinding Time: Depends on fineness required (usually hours).
4. Advantages for Chalk Making
– Produces ultra-fine powder (~10–50 microns).
– Homogeneous mixing of additives.
– Scalable for industrial production.
5. Alternatives & Considerations
– If producing school chalk, a simple hammer mill may suffice for coarser grinding.
– For ultra-fine chalk powder (e.g., for cosmetics), a planetary ball mill is better.
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