Raw Material Grinding
A heavy-duty ball mill that grinds proportioned limestone, clay, marl, and iron ore into fine cement raw meal. Available in dry-process and wet-process designs with capacities from 0.65 to 615 t/h — the essential grinding stage between crushing and clinker calcination.
Product Overview
The raw mill — also called the raw material mill or raw ball mill — is the grinding equipment that reduces crushed raw materials into the fine powder known as raw meal (or raw slurry in wet-process plants). After primary and secondary crushing reduces limestone, clay, sand, and iron ore to 0-25mm fragments, the raw mill further grinds these to a fineness of 80-90% passing 90μm, creating a chemically homogeneous raw meal ready for preheating and calcination in the rotary kiln.
In a dry-process cement plant, the raw mill also performs drying — hot waste gases from the preheater exhaust or a hot-air furnace pass through the mill, evaporating feed moisture (up to 8-12%) while grinding. This combined grinding-drying function makes the raw mill one of the most energy-intensive and critical pieces of equipment in the production line. In wet-process plants, water is added to produce a slurry of 30-40% moisture.
LIMING raw mills are designed as tumbling ball mills with a rotating cylindrical shell lined with wear-resistant steel or rubber liners. Grinding media (steel balls) cascade and cataract inside the shell, impacting and attriting the material. For dry-process applications with higher moisture, an integrated drying chamber is added at the feed end. Capacities range from 0.65 t/h for mini-plants to 615 t/h for large 10,000-TPD cement lines.
Key Benefits
Proven, robust design engineered for reliable continuous-duty grinding in cement plants.
Heavy-duty cast-steel or welded shell, oversized trunnion bearings, and high-quality liners deliver decades of reliable 24/7 operation in cement plants — tolerating feed variation and tramp metal.
Dry-process models include a drying chamber that uses preheater waste gas to evaporate up to 12% feed moisture — eliminating the need for a separate dryer and lowering energy cost.
Optimized liner profile, grinding media gradation, and compartment design maximize grinding efficiency. Central or edge drive options with single or dual pinion for any mill diameter.
Split-type liners and grinding media accessible via maintenance doors. Hydraulic mill-starting with jacking cradle. Compatible with high-efficiency separators for closed-circuit operation.
Technical Data
Representative dry-process raw mill models. Wet-process and custom sizes available on request.
| Model | Shell Ø × Length (m) | Capacity (t/h) | Grinding Media (t) | Motor Power (kW) | Speed (r/min) | Weight (t) |
|---|---|---|---|---|---|---|
| Ø1.2×4.5 | 1.2×4.5 | 0.65-1.5 | 5.0 | 55 | 34.8 | 13.5 |
| Ø1.5×5.7 | 1.5×5.7 | 2.2-3.5 | 12.0 | 130 | 29.5 | 23.0 |
| Ø1.83×7 | 1.83×7.0 | 4-6 | 21.0 | 245 | 25.0 | 35.0 |
| Ø2.2×7 | 2.2×7.0 | 8-10 | 33.0 | 380 | 22.5 | 48.0 |
| Ø2.4×8 | 2.4×8.0 | 12-16 | 45.0 | 570 | 21.0 | 62.0 |
| Ø2.6×13 | 2.6×13.0 | 22-28 | 78.0 | 1,000 | 20.0 | 96.0 |
| Ø3.0×9 | 3.0×9.0 | 28-40 | 85.0 | 1,250 | 18.5 | 118.0 |
| Ø3.2×10 | 3.2×10.0 | 40-55 | 100.0 | 1,600 | 18.0 | 140.0 |
| Ø3.5×10 | 3.5×10.0 | 55-70 | 120.0 | 1,900 | 16.5 | 165.0 |
| Ø3.8×7.5 | 3.8×7.5 | 70-85 | 125.0 | 2,250 | 15.8 | 185.0 |
| Ø4.0×13 | 4.0×13.0 | 90-120 | 190.0 | 3,200 | 15.2 | 260.0 |
| Ø4.2×13 | 4.2×13.0 | 110-145 | 210.0 | 3,800 | 15.0 | 290.0 |
| Ø4.6×14 | 4.6×14.0 | 180-240 | 285.0 | 5,000 | 14.0 | 390.0 |
| Ø5.0×15 | 5.0×15.0 | 300-420 | 360.0 | 6,500 | 13.5 | 485.0 |
| Ø5.4×16 | 5.4×16.0 | 450-615 | 430.0 | 8,000 | 13.0 | 620.0 |
* Specifications are for reference only. Actual capacity depends on material hardness, feed moisture, fineness requirement, and circuit configuration. Contact LIMING for custom sizing.
How It Works
The raw mill operates as a tumbling ball mill. The cylindrical shell rotates, lifting grinding media (steel balls) which then cascade and cataract down onto the raw material, crushing and grinding it by impact and attrition.
Frequently Asked Questions