The processing of kaolin varies greatly
from company to company. Each kaolin producer uses different equipment
and methods. Companies that use identical methods may use
them at different points during processing.
A good example of the extensive processing
of kaolin is found in those products intended for the paper
industry. The greatest demand for kaolin-based pigments comes
from the paper industry, which uses them to coat and fill papers
and boards. There are many ways to produce these pigments. One
of the methods used is called the "water washed process." Generally,
in the processing of water washed clays, water is used as a
transport and process medium involving the following:
||Fine particles, still in the form of slurry,
move on for further processing to enhance brightness.
- Brightness enhancement
With both the fine and coarse kaolin particle fractions,
brightness is enhanced through one or move processes including
bleaching, magnetic separation, flocculation, ozonation, flotation,
and oxidation, which will remove iron, titanium, organic,
and other undesirable materials.
For customers who want a delaminated clay product suited
for lightweight coating applications, coarse particles are
used. Delamination occurs as the coarse particles of kaolin
which when magnified appear as "booklets" are broken into
After delamination, the brightness of the coarse particles may
be enhanced through one or more of the same processes used in
the fine particle fraction.