We can supply washed kaolin,calcined kaolin and Metakaolin .
1. Washed Kaolin (Soft Kaolin, Non-calcined)
Test Item | Unit | Typical Spec (Premium Grade) | Remarks |
Appearance | — | Fine white powder | Free of coarse impurities |
Whiteness (R457) | % | ≥88.0 | High-grade coating ≥90 |
Al₂O₃ | % | 36.0～39.0 | |
SiO₂ | % | 47.0～50.0 | |
Fe₂O₃ | % | ≤0.40 | |
TiO₂ | % | ≤0.80 | |
Loss on Ignition (LOI) | % | 12.5～14.0 | Crystal water of kaolinite |
Moisture | % | ≤0.40 | Dry powder |
pH (10% suspension) | — | 5.0～7.0 | |
325 mesh residue (45μm) | % | ≤0.05 | |
Fraction <2μm | % | ≥75 | Coating grade ≥80 |
Properties | — | Retain natural kaolinite crystal, good plasticity & aqueous dispersibility |
2. Calcined Kaolin (Calcined at 900～1200℃)
Test Item | Unit | Typical Spec (Premium Grade) | Remarks |
Appearance | — | Pure white powder | |
Whiteness (R457) | % | ≥93.0 | Ultra-fine grade ≥94 |
Al₂O₃ | % | 42.0～45.0 | |
SiO₂ | % | 51.0～54.0 | |
Fe₂O₃ | % | ≤0.35 | Strict control for cable application |
TiO₂ | % | ≤0.70 | |
Loss on Ignition (LOI) | % | ≤0.50 | Crystal water removed |
Moisture | % | ≤0.50 | |
pH (10% suspension) | — | 6.0～8.0 | Nearly neutral |
325 mesh residue | % | ≤0.005 | |
Fraction <2μm | % | ≥82 | |
Oil Absorption | g/100g | 60～72 | Key index for coatings & inks |
Properties | — | Non-plastic; improved electrical insulation, hiding power & acid/alkali resistance |
3. Metakaolin (Low-temperature calcined 600～800℃, high pozzolanic activity)
Test Item | Unit | Type I High Activity Spec | Remarks |
Appearance | — | White / off-white powder | |
Al₂O₃ | % | ≥38.0 | |
SiO₂ | % | ≥52.0 | SiO₂+Al₂O₃ ≥90.0% |
Fe₂O₃ | % | ≤0.60 | Decorative grade ≤0.4 |
Loss on Ignition (LOI) | % | ≤1.60 | |
Moisture | % | ≤1.00 | |
45μm sieve residue | % | ≤1.0 | |
Water Demand Ratio | % | ≤120 | Critical for concrete |
28d Pozzolanic Activity Index | % | ≥95 | High-quality ≥100 |
Properties | — | Amorphous phase, high pozzolanic activity; mainly for concrete & mortar |
I. Common Processed Grades (Most Widely Used Industrial Classification)
1）Washed Kaolin (Soft Kaolin) Processed solely by physical beneficiation: pulping, desanding, classification, magnetic iron removal and drying. No calcination; natural crystal structure is retained. ✅ Features: Good plasticity, platy structure, excellent dispersibility in aqueous systems ✅ Applications: Paper coating, domestic ceramics, ceramic glazes, water-based coatings
2）Calcined Kaolin Manufactured by calcining washed kaolin or coal-measure kaolin at 900～1200℃ to remove crystal water and destroy the crystal structure. ✅ Features: Loss of plasticity, higher whiteness, developed pores, electrical insulation, acid & alkali resistance and enhanced hiding power ✅ Applications: Filler for wires and cables, engineering plastics, anti-corrosion coatings, printing inks, refractory materials
3）Metakaolin Product obtained by low-temperature calcination at 600～800℃ with high activity, mainly used as a high-performance admixture for concrete.
II. Main Industrial Applications
Ceramic Industry (Traditional Core Application)
Increases Al₂O₃ content in ceramic bodies, raises firing temperature, reduces deformation, and improves the whiteness and strength of finished ceramics. It is an essential raw material for domestic ceramics, architectural ceramics, electrical porcelain and special ceramics.
Paper Industry
The largest consumption sector. Used as filler and coating pigment to fill voids between fibers, improving paper smoothness, whiteness and printability (for coated art paper, picture albums, etc.).
Coatings & Printing Inks
Washed kaolin is applied in water-based coatings. Calcined kaolin can partially replace titanium dioxide, improving film hardness, anti-settling performance, weather resistance and anti-corrosion properties.
Rubber & Plastics Industry
Calcined kaolin serves as a reinforcing filler to enhance the gas tightness of rubber. In plastics, it improves electrical insulation and dimensional stability for cables, pipes and other products.
Refractory Materials
High-alumina kaolin is made into refractory bricks and castables for metallurgical kilns.
Daily Chemicals, Pharmaceuticals & Agriculture
High-purity kaolin: facial masks, face powder, toothpaste (oil absorption); pharmaceutical carriers; carriers for pesticides and fertilizers; food-grade grade used as anti-caking agent.
Emerging Fields
Catalyst carriers, raw material for molecular sieves, lithium battery materials, environmental adsorption materials.
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