China Clay (Kaolin) Processing Plants
Custom-tailored kaolin washing systems that deliver the particle size and brightness each user industry demands.
China clay (kaolin) processing washes crude clay with water to achieve grit removal, sizing, attrition, filtering and drying. Brightness is raised by magnetic separation, flocculation or flotation to remove iron and titanium: Fe levels of around 1.5% in recovered clay are brought below 1%, delivering 90–92% whiteness at 300 mesh.
What is china clay?
Kaolin (china clay) is a hydrated aluminium silicate crystalline mineral (kaolinite), formed over millions of years by the hydrothermal decomposition of granite rocks. Hydrous kaolin is characterised by its fine particle size, plate-like or lamellar particle shape and chemical inertness.
Clay serves the rubber, paper, ceramic, glass, paint and plastic industries, each requiring different grades by particle size and mineral content. Paper coating sits at the top of the value chain, while ceramic grades are more generic.
The washing and brightening process
Clay pigments are produced through a washing system with water as the process medium, achieving grit removal and sizing, and providing attrition, filtering and drying. Silica sand is often produced as a by-product, with uses in the glass industry, foundry sand and construction.
Brightness of clay fractions is achieved by one or more processes, magnetic separation, flocculation or flotation, removing iron, titanium, organic and other undesirable material. High-quality clay is evaluated on particle size range and L value (brightness). In our reference work, Fe was brought down from around 1.5% in the recovered clay to the desired level of below 1%, with TiO2 not an issue in that clay. CFlo has undertaken extensive test work across the classification technologies the company has evolved over the years to generate the specific fractions each user industry demands.
Product grades and typical characteristics
CFlo systems produce the full commercial range: levigated china clay powder, water-washed china clay powder, natural kaolin powder, and water-washed and natural lumps. Typical characteristics include:
- Whiteness: 90–92% for levigated and water-washed powders; 88–90% for natural kaolin powder
- Moisture: below 0.5% across all grades
- Particle size: 300 mesh powders with a 50 micron top cut
- Chemistry: levigated grade at 47–48% SiO2 and 37–39% Al2O3; natural kaolin at 74–75% SiO2 and 16–17% Al2O3
- Applications: paints, plastics, paper and cosmetics for washed powders; ceramics and rubber for natural grades
Custom-tailored, on the Micrograder platform
Each clay processing system is custom-tailored to the particle size distribution and chemical composition of your feed. The platform is CFlo's Micrograder fine classification range, running in the field at Suraj Minerals (published case study), and engineered as a Next-Gen 'Super' System: Super modular, Super smart process control that holds brightness and sizing while reducing water and power, Super easy app-guided installation and service.
Frequently asked questions
What industries buy processed china clay?
Rubber, paper, ceramic, glass, paint and plastics industries all use kaolin, each with its own grade requirements for particle size and mineral content. Paper coating is the highest-value application; ceramic grades are more generic. Washed powders also serve the cosmetics industry.
How is kaolin brightness improved?
Brightness (L value) is raised by removing iron, titanium, organics and other undesirable material through one or more of magnetic separation, flocculation or flotation. In CFlo's reference work, Fe was reduced from around 1.5% in the recovered clay to below 1%, meeting the brightness target without TiO2 treatment.
What particle size does processed china clay achieve?
Standard powder grades are 300 mesh with a 50 micron top cut, across levigated, water-washed and natural kaolin products. Generating the specific fractions each industry demands is classification work, and CFlo has run extensive test work across its classification technologies to prove each cut.
What whiteness can a kaolin washing plant deliver?
Levigated and water-washed china clay powders typically reach 90–92% whiteness, natural kaolin powder 88–90%, and lump products 88–90%, all at below 0.5% moisture. The achievable figure depends on your feed chemistry, which is why every CFlo system is tailored after feed analysis.
Is anything else recovered from china clay processing?
Yes. Silica sand is often produced as a by-product of the washing system, with ready markets in the glass industry, foundry sand and construction. That by-product revenue improves overall project economics alongside the primary clay grades.
Why is every kaolin plant custom-tailored?
Because feed varies: each clay processing system is designed around the particle size distribution and chemical composition of your specific deposit, and around the grades you intend to sell. CFlo confirms the flowsheet through test work before the modular Micrograder-based plant is built.
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