China Clay Powder Price And Uses
China Clay Powder: Price Factors and Industrial Uses
Overview
China clay, also known as kaolin, is a naturally occurring hydrous aluminum silicate mineral with the chemical formula Al₂Si₂O₅(OH)₄. It is valued for its fine particle size, typically ranging from 0.5 to 5 µm, and its high whiteness after processing.
Key Properties
Important technical characteristics include brightness (ISO whiteness), particle size distribution, loss on ignition (LOI), bulk density, and pH of aqueous slurry. These parameters directly influence performance in downstream applications such as ceramic bodies and paper coating.
| Property | Typical Value | Test Method |
|---|---|---|
| Brightness (ISO) | 85‑95 % | ISO 2470 |
| Particle Size d50 | 1.5‑3.0 µm | Laser diffraction |
| Loss on Ignition (LOI) | 12‑14 % | ASTM C373 |
| Bulk Density | 0.4‑0.6 g/cm³ | ASTM C110 |
| pH (10 % slurry) | 4.5‑5.5 | ASTM D1293 |
Industrial Applications
In ceramic manufacturing, china clay acts as a flux‑reducing agent that improves green strength and reduces firing shrinkage, leading to tighter dimensional tolerances in sanitaryware and tableware.
The paper industry uses calcined kaolin as a coating pigment because its platy particles enhance opacity, ink holdout, and surface smoothness, which increases print quality and reduces ink consumption.
In paints and coatings, the mineral functions as an extender and rheology modifier, providing sag resistance and improving film hardness without significantly affecting color.
Rubber and plastic compounders add kaolin to increase stiffness, improve abrasion resistance, and reduce material cost while maintaining flexibility.
Price Influencing Factors
The cost of china clay powder varies primarily with purity level, particle size grading, moisture content, and the degree of processing (e.g., water‑washed, calcined, surface‑treated).
- Higher brightness and lower iron oxide content command a premium.
- Ultra‑fine grades (<1 µm d50) require additional milling steps, increasing price.
- Low moisture (<0.5 %) reduces shipping weight and prevents clumping, affecting unit cost.
- Bulk shipments in railcars or silos lower packaging expense compared to 25 kg multi‑wall bags.
- Order volume influences freight rates and possible volume discounts.
Handling and Storage
Kaolin is hygroscopic; exposure to humid environments can cause agglomeration and affect flowability. It should be stored in dry, ventilated areas with temperature control below 30 °C.
Packaging options include multi‑wall paper bags with polyethylene liner, flexible intermediate bulk containers (FIBCs), and pneumatic bulk tankers for large‑volume consumers.
Quality Control and Testing
Suppliers typically provide a certificate of analysis covering brightness, particle size distribution (laser diffraction), chemical composition (XRF), loss on ignition, and residue on sieve (45 µm). Regular batch testing ensures consistency for sensitive applications such as paper coating.
Customization Options
Depending on end‑use, the powder can be calcined at temperatures between 600 °C and 900 °C to increase brightness and abrasiveness, or surface‑treated with silanes to improve compatibility with polymeric matrices.
Custom particle size grading, moisture reduction, and additive blending (e.g., with titanium dioxide) are available upon request to meet specific formulation targets.
Frequently Asked Questions
Can the particle size distribution be tailored?
Yes, milling and classification allow adjustment of d50 and d97 values to suit coating or filler requirements.
What information is needed for a quotation?
Required details include desired brightness range, particle size specification, moisture limit, order quantity, packaging preference, and delivery destination.
How is quality verified before shipment?
Each lot undergoes inline brightness monitoring and final laboratory testing; a co‑signed certificate of analysis accompanies the shipment.
For a detailed quotation, technical datasheet, or to discuss specific grade requirements, please contact our sales team.
Request Quote and Technical Data