Raw mill ball mill (also called raw material ball mill or raw mill) is the key grinding equipment used in cement production lines to crush and grind raw materials such as limestone, clay, shale, iron ore, and sandstone into fine powder, known as raw meal. This raw meal is then homogenized and fed into a rotary kiln for clinker production.
Raw mill ball mill (also called raw material ball mill or raw mill) is the key grinding equipment used in cement production lines to crush and grind raw materials such as limestone, clay, shale, iron ore, and sandstone into fine powder, known as raw meal. This raw meal is then homogenized and fed into a rotary kiln for clinker production.
Our raw mill ball mill is a heavy‑duty, closed‑circuit system with integrated drying capability. Most raw materials contain 3–15% moisture, so the mill is designed to simultaneously dry and grind using hot gases from the kiln or a hot air generator. The mill features a horizontal rotating cylinder divided into two or three grinding chambers with wear‑resistant liners. As a professional ball mill manufacturer, we provide complete raw material grinding solutions for cement plants, including wet and dry processes.
Applicable materials: limestone (CaCO₃), clay, marl, shale, iron ore, sandstone, bauxite, gypsum, and other cement‑grade raw materials.
Step 1 – Feeding & Hot Gas Inlet
Raw materials (limestone, clay, iron ore, etc.) are fed via a weigh belt feeder. Hot gas (150–250°C) from the kiln or a hot air generator enters the mill inlet, flowing through the mill.
Step 2 – Coarse Grinding & Drying
In Chamber 1, large steel balls impact‑crush limestone lumps. Hot gas evaporates surface moisture from the material.
Step 3 – Material Flow to Second Chamber
Partially ground material passes through a slotted diaphragm into Chamber 2. The diaphragm retains grinding media.
Step 4 – Fine Grinding & Drying
Chamber 3 (or Chamber 2 in two‑chamber designs) contains small steel balls and classifying liners. Fine grinding produces raw meal. Hot gas continues to dry the material, now finely dispersed.
Step 5 – Classification & Collection
Material exits the mill and is lifted to a dynamic air classifier. Fines (raw meal meeting fineness target) are collected by a bag filter. Coarse particles return to the mill. The exhaust gas passes through the bag filter, where dust is collected and hot gas is vented (or recycled).
Unlike standard ball mills, our raw mill accepts feed with up to 15% moisture. Hot gas (150–250°C) from the kiln pre‑heater or a dedicated hot air generator is drawn through the mill, evaporating moisture during grinding. This eliminates a separate dryer, saving capital and operating costs.
For stable kiln operation, raw meal fineness must be controlled (typically 8–12% residue on 90µm sieve). Our high‑efficiency dynamic classifier (V‑separator) ensures sharp particle size distribution with minimal oversize. The PLC system automatically adjusts classifier speed to maintain target fineness.
Our closed‑circuit raw mill reduces over‑grinding and cuts specific energy consumption to 18–25 kW·h/t (compared to 25–35 kW·h/t for open circuit). Adding a roller press before the mill can lower energy to 12–18 kW·h/t.
Raw materials often contain quartz or iron ore. We line the mill with high chromium cast iron (HRC ≥58) and use forged alloy steel balls with breakage rate <0.5%. For extreme abrasion, we offer ceramic lining and alumina grinding media.
| Model | Dia.×Length (m) | Capacity (t/h) * | Fineness (90µm residue) | Motor Power (kW) |
|---|---|---|---|---|
| Φ2.2×7.5m | 2.2×7.5 | 10–15 | 10–12% | 380 |
| Φ2.4×10m | 2.4×10 | 18–25 | 10–12% | 630 |
| Φ2.6×13m | 2.6×13 | 30–40 | 8–10% | 1000 |
| Φ3.0×11m | 3.0×11 | 45–55 | 8–10% | 1250 |
| Φ3.2×13m | 3.2×13 | 60–80 | 8–10% | 1600 |
| Φ3.8×13m | 3.8×13 | 90–120 | 8–10% | 2500 |
| Φ4.2×14.5m | 4.2×14.5 | 140–180 | 8–10% | 3150 |
Capacity based on limestone with Bond Work Index 12–14, feed ≤20mm, moisture 5%, target 90µm residue 10%. Add 20% for dryer materials.
| Hot Gas Temperature | Max. Feed Moisture | Residual Moisture |
|---|---|---|
| 150°C | 8% | <1% |
| 200°C | 12% | <1% |
| 250°C | 15% | <1% |
| Parameter | Value |
|---|---|
| Max. feed size | ≤20–30 mm |
| Output fineness (90µm sieve) | 8 – 12% (adjustable) |
| Blaine specific surface | 200 – 350 m²/kg |
| Max. feed moisture | ≤15% (with hot gas) |
| Residual product moisture | <1% |
| Grinding method | Dry with drying |
| Circuit type | Closed‑circuit (mandatory) |
| Number of chambers | 2 or 3 |
| Liner material | High chromium cast iron (HRC ≥58) / Ceramic (optional) |
| Grinding media | Forged steel balls / High chromium balls |
| Optional features | Roller press pre‑grinding, dynamic V‑separator, bag filter, hot gas generator |
When selecting a raw material ball mill, consider these seven factors:
Raw material composition & hardness – Provide a sample for Bond Work Index testing. Typical limestone: Wi = 10–14; clay: Wi = 8–10; iron ore: Wi = 12–16.
Feed moisture – Below 5%: standard dry mill (may not need hot gas). Above 5%: you need a drying‑grinding mill with hot gas inlet.
Target fineness – For dry process cement kilns, typical raw meal fineness is 8–12% residue on 90µm sieve. Specify your requirement.
Capacity requirement – State your required tons per hour. We will match the optimal raw mill ball mill capacity.
Energy efficiency expectations – A closed‑circuit raw mill is essential. For higher capacity or harder materials, consider adding a roller press as a pre‑grinder.
Available heat source – If you have kiln exhaust gas (200–350°C), we can design the system to use that waste heat. Otherwise, we supply a hot air generator.
After‑sales support – Installation, commissioning, training, and spare parts. Our team provides 24/7 support.
Raw mill grinding is unique because it must simultaneously dry and grind materials with varying moisture levels. Two critical factors determine success: drying capacity and grindability balance.
| Feed Moisture | Without Drying | With Drying‑Grinding Mill |
|---|---|---|
| <3% | Acceptable – may still need dust control | Not necessary |
| 3–8% | Poor output, clogging, high maintenance | Recommended – stable operation |
| 8–15% | Impossible – mill stops frequently | Required – integrated drying |
Raw meal typically contains 70–80% limestone (hard), 10–20% clay (soft), and 5–10% iron ore/sandstone (hard). Our mill uses a graded ball charge across chambers:
| Chamber | Ball Size | Function | Material Targeted |
|---|---|---|---|
| 1 | Φ70–100 mm | Impact crushing | Limestone lumps, sandstone |
| 2 | Φ40–60 mm | Coarse grinding | Limestone, iron ore |
| 3 | Φ15–40 mm | Fine grinding | Clay, limestone fines |
We perform a detailed heat balance to determine:
Required hot gas temperature and flow rate
Mill outlet temperature (typically 80–100°C to avoid condensation)
Bag filter sizing
Pro tip: For raw materials with very high moisture (>12%), we recommend a separate pre‑drying stage (flash dryer) before the mill, followed by the drying‑grinding mill. This reduces hot gas consumption and prevents mill overload. We can design both configurations.
ISO9001 & CE certified – Strict quality control from raw material to final assembly.
20+ years in cement grinding equipment – Specialized in raw mill ball mills for cement plants worldwide.
Integrated drying expertise – We design hot gas systems using kiln waste heat or standalone generators.
Wear‑resistant materials – High chromium liners (HRC ≥58) and forged balls for long life.
Energy‑efficient closed‑circuit – Reduces power consumption by 15–20% compared to open circuit.
Full process support – Lab test (grindability, drying curve) → engineering → manufacturing → installation → commissioning → training.
Global service network – Engineers available for on‑site visit and 24/7 remote troubleshooting.
Kolev Equipment Technology Co., Ltd. is a large-scale private technology enterprise specializing in the research, development, production, and sales of mining and metal ore processing equipment. With over 20 years of experience in ultra-fine grinding, industrial drying, and crushing sand making industries, we provide intelligent solutions and mature supporting products worldwide.
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