Calcite Powder
Calcite Powder Manufacturer & Bulk Supplier for Paints, Coatings and Industrial Applications
Industrial-grade fine ground calcite powder featuring ultra-high chemical purity (CaCO3 >= 99%), exceptional brightness, low heavy metal residues, and narrow particle size distribution for high-end coatings, engineering plastics, and sealants.
Calcite powder (CaCO3) is processed from selected high-purity natural calcite crystal reserves through multi-stage magnetic separation, precision vertical roller milling, and closed-circuit turbo air classification. Due to its pure rhombohedral crystal structure, it exhibits high chemical inertness, excellent light scattering properties, and low oil absorption. Processing parameters—including milling intensity, magnetic iron removal stages, and classifier rotor speed—are rigorously controlled to ensure stable brightness, targeted median particle size (d50), and strict top-cut (d97) boundaries.
Product Grades & Specifications
Ultra-White & High-Purity Grade (d50: 2 - 5 um):
Formulated for premium architectural coatings, automotive primers, and engineering plastics demanding maximum brightness and zero dark speck contamination.
Standard Industrial Fine Grade (d50: 8 - 12 um / 600 mesh):
Optimized for general plastic compounds, rubber goods, adhesives, and sealants where balanced rheology and cost-efficiency are required.
Surface-Modified (Activated) Grade:
Encapsulated with high-purity stearic acid (1.0% - 1.5%) for enhanced hydrophobicity, uniform dispersion, and strong interfacial bonding in polymer matrices.
Technical Data Table
|
Parameter |
Ultra-White High-Purity Grade |
Standard Industrial Fine Grade |
Surface-Modified Activated Grade |
Testing Method |
|
Calcium Carbonate (CaCO3) |
>= 99.0% |
>= 98.0% |
>= 97.5% (Core) |
EDTA Titration / XRF |
|
Whiteness / Brightness |
>= 95.0% |
>= 93.0% |
>= 93.0% |
ISO 787-7 Spectrophotometer |
|
Mean Particle Size (d50) |
2.5 - 4.5 um |
8.0 - 12.0 um |
3.0 - 6.0 um |
Laser Particle Size Analyzer |
|
Top Cut Particle Size (d97) |
<= 12 um |
<= 35 um |
<= 15 um |
Laser Particle Size Analyzer |
|
Iron Oxide (Fe2O3) |
<= 0.03% |
<= 0.05% |
<= 0.05% |
Atomic Absorption / XRF |
|
Acid Insoluble Matter |
<= 0.2% |
<= 0.5% |
<= 0.5% |
Gravimetric Analysis |
|
Oil Absorption Value |
16 - 20 g/100g |
13 - 17 g/100g |
15 - 19 g/100g |
ISO 787-5 |
|
Moisture Content |
<= 0.2% |
<= 0.3% |
<= 0.2% |
Infrared Moisture Balance |
|
Surface Activation Rate |
Untreated |
Untreated |
>= 98.0% Bound Acid |
Solvent Extraction / Titration |
Industrial Applications
Coatings & Paints: Serves as a primary white extender pigment in architectural and industrial finishes. Its high refractive index and low impurity profile improve opacity, tint retention, and weathering resistance while optimizing titanium dioxide (TiO2) spacing.
Engineering Plastics & Masterbatches: Used as a functional mineral filler in polyolefins (PP/PE), PVC, and engineering plastics. It enhances tensile modulus, thermal dimensional stability, and impact resistance without sacrificing elongation.
Sealants & Adhesives: Incorporated into silicone, polyurethane, and acrylic sealants to control extrusion rheology, reduce material costs, and prevent post-curing shrinkage.
Rubber Compounding: Acts as a reinforcing filler in industrial rubber hoses, automotive weatherstripping, and molded items, improving tear strength and hardness.
Specialty Chemicals & Pharmaceuticals: Functions as a high-purity calcium source and pH buffer in industrial chemical synthesis and specialized formulations.
Quality Control & Testing
Raw Crystal Selection & Sorting:
Natural calcite raw ore blocks undergo manual sorting and high-intensity rare-earth magnetic separation to remove iron-bearing impurities and ensure raw material purity above 99%.
Precision Air Classification:
Closed-circuit grinding systems integrated with high-efficiency turbo classifiers strictly regulate the top-cut (d97), eliminating oversized particles that cause surface defects.
Real-Time Laboratory Testing:
Hourly sampling is analyzed using laser diffraction particle size analyzers, whiteness meters, and EDTA titration to verify compliance with technical specifications.
Activation Verification:
For surface-modified grades, free fatty acid content and contact angle testing confirm complete and uniform stearic acid bonding on every calcite particle.
Custom Particle Size & Packaging
Available Granulometry & Surface Options
Micro-Fine Grades (d50: 2 - 5 um): Uncoated or activated with precise dosages of stearic acid for polymer compatibility.
Custom Distribution Curves: Tailored d50 and d97 specifications designed to meet specific viscosity and packing density targets.
Secure Packaging Solutions
High-purity calcite powder is hydroscopic under extreme humidity and requires robust containment to maintain free-flowing properties:
25 kg Multi-Wall Paper Bags: Polyethylene-lined kraft paper bags palletized and stretch-wrapped with weather-resistant hoods.
1,000 kg / 1,200 kg FIBC Jumbo Bags: Heavy-duty woven polypropylene bulk bags equipped with inner PE liners and bottom discharge spouts for closed-system pneumatic conveying.
Bulk Powder Tanker Trucks: Direct pneumatic loading into factory storage silos for high-capacity manufacturing facilities.
Bulk Supply & Export Logistics
Monthly Capacity:
40,000 Metric Tons of high-purity calcite powder products.
Storage & Handling:
Enclosed vertical storage silos equipped with automated moisture monitoring and fluidization systems to prevent caking.
Export Containers:
Loaded in 20-foot dry containers (24 to 26 MT per FCL depending on destination port weight limits).
Documentation:
Complete batch shipment paperwork including Certificate of Analysis (CoA), Safety Data Sheet (SDS), Commercial Invoice, Packing List, and Certificate of Origin (CoO).
Our Certificate
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Q: What is the difference between Calcite Powder and general Limestone Powder?
A: Calcite powder is derived from high-purity crystallized calcium carbonate minerals (calcite single crystals or pure calcite rock) with a defined rhombohedral structure, typically offering higher chemical purity (CaCO3 >= 99%), superior brightness, and lower heavy metal or iron content than standard run-of-quarry limestone.
Q: How does strict control of the top-cut particle size (d97) benefit my application?
A: The top-cut (d97) dictates the maximum particle size present in the powder. Controlling the d97 prevents surface blemishes and micro-scratches in thin plastic films, eliminates nozzle clogging in spray-applied coatings, and ensures smooth dispersion.
Q: Do you offer surface-modified calcite powder for plastic compounding?
A: Yes. We offer calcite powder surface-treated with high-purity stearic acid (typically 1.0% to 1.5%). This coating converts the hydrophilic mineral surface into a hydrophobic one, improving dispersion, reducing compound melt viscosity, and increasing impact strength in polymer matrices.
Q: How do you prevent black specks and iron contamination in high-purity grades?
A: We employ multi-stage rare-earth magnetic separators during crushing and grinding, combined with strict visual and XRF sorting of raw calcite ore, ensuring iron oxide (Fe2O3) levels remain below 0.03% to eliminate dark speck defects in white finishes.
Q: How do you protect the powder from moisture absorption during ocean freight?
A: All export packages—including 25 kg paper bags and 1,000 kg jumbo bags—feature heat-sealed internal polyethylene liners. Pallets are fully enclosed in heavy-duty stretch film to isolate the mineral powder from maritime humidity during long-distance transit.
Q: What is the standard Minimum Order Quantity (MOQ) for custom particle grades?
A: The standard MOQ for custom particle size distributions or specialized surface-activated grades is one 20-foot container (approx. 24 Metric Tons), ensuring efficient pallet configuration and dedicated batch production.