A roller mill is an industrial equipment that crushes, grinds, or refines solid materials through compression and friction between rotating rollers. It can have one, two, three, or more rollers, depending on the application.
The material is fed between the rollers, where it is crushed until it reaches the desired particle size. It is used in the chemical, cement, food, coal, ceramic, and metallurgical industries.
The roller mill is used to:
- Reduce large particles into smaller particles (grinding).
- Homogenize mixtures and ensure product uniformity.
- Pre-crushing raw materials before other processes.
- Particle size control in final products (e.g., chocolate or pigments).
Types of roller mills:
- Single roller mill:
Principle: A single roller compresses the material against a fixed surface.
Characteristics: Low capacity, suitable for soft or friable materials.
Industries that use it: ceramics (clays), small coal industries, and pre-crushing of friable minerals.
- Double roller mill:
Principle: Two rollers rotating in opposite directions crush the material.
Characteristics: More efficient than the single roller; continuous and uniform grinding.
Industries that use it: cement (pre-grinding of limestone), pulverized coal, chemical industry (minerals, gypsum), clays and ores.
- Three-cylinder roller mill (3 rollers):
Principle: Two lower rollers and one upper roller compress the material gradually.
Characteristics: Higher capacity, uniform particle size, fewer unwanted fines.
Industries that use it: cement (grinding of clinker and limestone), pigments and fine chemicals, pulverized coal, food (chocolate, peanut butter, cocoa, sweets), and the PET and veterinary industry.
- Multi-roller mills (4 or more rollers):
Principle: Several rollers compress the material; generally used for fine grinding or precise particle size control.
Characteristics: High uniformity, suitable for hard or sensitive materials.
Industries that use them: hard ores and metals, fine pigments, specialty chemicals, gourmet chocolates, and high-quality food pastes.
Roller mills can be manufactured with different materials, depending on the application, abrasiveness of the material to be ground, and hygiene or corrosion resistance requirements.
Carbon steel: This is the most common material in mills used in the cement, coal, and mining industries. It offers good mechanical resistance and is relatively inexpensive, making it ideal for abrasive and heavy materials.
Cast iron: Used in heavy industries, especially for ores and highly abrasive materials. Cast iron has high abrasion resistance and good mechanical performance, but is heavier and less resistant to corrosion.
Stainless steel (inox): Essential in the food, pharmaceutical, and fine chemical industries, where hygiene and corrosion resistance are fundamental. Stainless steel prevents product contamination and facilitates cleaning, making it ideal for grinding chocolate, cocoa, food pastes, and sensitive chemical powders.
Steel with special coatings (rubber, ceramic, or polymers): Used for highly abrasive or contamination-sensitive products. The coating reduces equipment wear, protects the material, and prevents unwanted chemical reactions. |
