How to Choose a Calcium Carbonate Mill According to Raw Material Type

Calcium carbonate raw materials differ drastically in hardness, moisture, impurity content, block size, whiteness and mineral structure. Each raw material requires a matched grinding mill, otherwise it will cause low output, high energy consumption, serious equipment wear, poor powder whiteness or unqualified fineness. This guide classifies common CACO3 raw materials and corresponding matching grinding equipment, plus key selection criteria.

1. Classification of mainstream calcium carbonate raw materials & matched mills

Category 1: Natural calcite ore (Most widely used raw material)

Raw material characteristics

• Hardness: Mohs 3, soft mineral, easy to grind
• Original block size: 50–300mm lump ore after mining
• Moisture: 2%–10% (mine surface ore has high water content; deep mine dry ore ≤4%)
• Advantages: High whiteness, low silicon/iron impurities, suitable for plastic, paint, papermaking GCC

Matching mill solutions

1. Output ≥8t/h, 400–2500 mesh, continuous mass production, high moisture ore (5%–12%)
   HLMX Superfine Vertical Roller Mill (Best choice)
   Built-in hot air drying handles wet calcite directly; material bed grinding reduces roller wear; stable ultrafine output, low energy consumption.
2. Output 1–8t/h, 800–2000 mesh, small batch dry calcite (moisture ≤5%)
   HGM Multi-Ring Ultrafine Roller Mill
   Low initial investment, flexible grade switching for small orders of masterbatch/paint filler.
3. Output ≤5t/h, only 80–400 mesh coarse powder (mortar, feed, desulfurization)
   Raymond Mill
   Simple structure, low cost for single-spec coarse calcite powder.

Category 2: Marble stone waste / marble scraps

Raw material characteristics

• Mohs hardness 3–3.5, slightly harder than calcite
• Raw material: irregular waste blocks, leftover stone slabs, stone powder sludge
• Moisture: Sludge marble waste moisture up to 15%–25%; dry block scraps ≤6%
• Defect: Partial marble contains trace iron/manganese, easy to reduce powder whiteness

Matching mill solutions

1. Wet marble sludge / high moisture marble scraps (moisture＞8%), large output
   HLMX Vertical Roller Mill with enhanced drying system
   Strengthened hot air circulation to evaporate high moisture; thickened high-chromium alloy roller/table to resist slightly harder marble abrasion.
2. Dry marble block waste, small batch ultrafine powder
   Upgraded wear-resistant HGM multi-ring mill
3. Marble stone sludge for super-fine coating powder (＞2500 mesh)
   Wet stirred media grinding line (sludge direct feeding without drying in advance)

Category 3: Limestone ore (Low-end industrial filler only)

Raw material characteristics

• Mohs 3, many interlayer impurities (clay, silicon oxide), low whiteness
• Main application: construction mortar, flue gas desulfurization, animal feed, low-cost rubber filler
• Coarse powder demand mostly 80–400 mesh, rarely above 600 mesh

Matching mill solutions

1. Large desulfurization/construction filler production line ≥8t/h
   Standard LM Vertical Roller Mill
2. Small workshop low-output coarse powder
   Ordinary Raymond Mill

Not recommended: HGM ultrafine mill, vertical superfine mill

High cost with no demand for high fineness; limestone impurities accelerate wear parts loss.

Category 4: Chalk / white chalk ore

Raw material characteristics

• Extremely soft, Mohs 2, loose porous structure, ultra-easy grinding
• Natural moisture high (8%–18%), easy agglomerate after crushing
• High natural whiteness, ideal for high-grade papermaking, cosmetics filler

Matching mill solutions

1. High moisture chalk bulk production
   HLMX vertical mill with low-temperature drying system
   Low-temperature hot air avoids chalk powder yellowing; soft raw material greatly reduces equipment wear, ton power consumption further reduced.
2. Small batch activated ultrafine chalk powder
   HGM multi-ring ultrafine mill

Category 5: Precipitated Calcium Carbonate (PCC, wet cake raw material)

Raw material characteristics

Chemical synthesis wet filter cake, moisture 30%–45%, ultra-fine primary particle, agglomerated seriously, cannot use dry mill directly

Matching mill solutions

1. Dry-process PCC finished powder (after flash drying)
   HLMX vertical mill for de-agglomeration, disperse agglomerated PCC to uniform D50
2. Wet slurry PCC for coating pigment
   Continuous batch wet stirred media mill

Forbidden: Ordinary Raymond / HGM mill

High-moisture PCC cake will block grinding cavity, cause sticking and shutdown.

Category 6: Waste calcium carbonate powder / recycled stone powder

Raw material characteristics

Already crushed semi-finished powder, mixed coarse and fine particles, low bulk density, easy floating dust

Matching mill solutions

1. Reprocess to uniform high-fineness powder for plastic
   HLMX vertical mill with closed circulation classification
2. Small recycling batch production
   HGM ultrafine mill with sealed feeding device

Advantage: Raw material pre-crushed reduces mill load, lower power consumption.

2. Key raw material indicators that determine mill selection

2.1 Raw material hardness (Mohs scale)

1. Soft raw materials (chalk, pure calcite Mohs ≤3): All mill types are applicable; priority vertical mill for energy saving.
2. Medium hardness (marble Mohs 3–3.5): Must select equipment with thickened high-chromium alloy wear parts (vertical mill / upgraded HGM mill).
3. Hard mixed impurity ore (limestone with silica): Avoid high-fineness ultrafine mills; vertical mill with wear-resistant lining is the best choice.

2.2 Raw material moisture content (core dividing line: 5%)

1. Moisture ≤5% (dry lump ore): Raymond, HGM, vertical mill all available
2. Moisture 5%–12%: Only vertical roller mill with integrated drying works; HGM/Raymond need additional independent dryer (increase energy consumption and failure points)
3. Moisture ＞15% (marble sludge, PCC wet cake):
   • If final product is dry powder: HLMX vertical mill with enhanced drying
   • If final product is slurry coating pigment: Wet stirred grinding line

2.3 Raw material feeding block size

1. Lump ore 50–300mm: Must configure two-stage crushing (jaw crusher + impact crusher) before all mills; vertical mill bears larger feeding size than HGM/Raymond.
2. Pre-crushed fine raw material (＜10mm): Smaller mill load, energy consumption decreases by 5%–10%.

2.4 Impurity & whiteness requirement of raw ore

1. High whiteness demand (calcite for paint/paper): Choose vertical mill with material bed non-metal-contact grinding to avoid iron contamination; reject ball mills with steel liner.
2. High iron/silicon impurity limestone: Only for low-end coarse powder, do not invest in ultrafine grinding equipment.

3. Step-by-step selection flow based on raw material

1. Confirm raw material type: Calcite / marble / limestone / chalk / PCC wet cake / recycled stone powder
2. Test three core raw indicators: Mohs hardness, moisture percentage, feeding lump size
3. Clarify target finished fineness and hourly output
4. Judge moisture first:
   • Moisture＞5%: Prioritize HLMX vertical roller mill
   • Moisture ≤5%: Select vertical mill (large output) or HGM/Raymond (small output)
5. Judge hardness: Medium-hard marble requires wear-resistant reinforced model
6. Special raw material exclusive matching: PCC wet cake → wet stirred mill; limestone low-end filler → Raymond / standard vertical mill
7. Verify supporting configuration: Drying system, alloy wear parts, sealed feeding according to raw material characteristics

4. Summary

1. Pure dry calcite (moisture ≤5%, Mohs 3):
   Large continuous production → HLMX vertical mill; small batch ultrafine → HGM mill; coarse filler → Raymond mill
2. High moisture ore / marble sludge (moisture＞5%): HLMX vertical roller mill (unique integrated drying advantage)
3. Marble waste (slightly harder): Wear-resistant upgraded vertical mill or HGM mill
4. Limestone low-end coarse filler: Standard LM vertical mill / Raymond mill
5. Chalk soft high-moisture ore: Low-temperature drying HLMX vertical mill
6. PCC wet filter cake: Wet stirred media grinding line
7. Avoid mismatching: Do not use dry mills to process high-moisture sludge/PCC cake; do not use ultrafine mills for low-grade limestone coarse powder.

JACAN customizes calcium carbonate mill wear-resistant liners, drying systems and feeding structures targeted at different raw mineral materials, solving blocking, excessive wear, high moisture sticking and whiteness reduction problems for various calcite, marble, limestone and recycled powder production lines.